Find the best tutors and institutes for Class 11 Tuition
Q5.15(i):
Two bodies of masses 10 kg and 20 kg respectively kept on a smooth, horizontal surface are tied to the ends of a light string. A horizontal force $F = 600 N$ is applied to (i) A, along the direction of string. What is the tension in the string in each case?
Solution :
Given Variables & Initial Setup
Let $m_1 = 10\text{ kg}$ (Body A) and $m_2 = 20\text{ kg}$ (Body B). Both bodies are connected by a light (massless) string on a smooth (frictionless) horizontal surface. An external force $F = 600\text{ N}$ is applied to body A (the 10 kg mass) in the direction of the string, pulling body B behind it.
Step 1: Calculating the Acceleration of the System
Since the bodies are tied together by a light string, they move as a single composite system with common acceleration $a$ [Per Newton's Second Law of Motion].
The total mass of the system is $M = m_1 + m_2 = 10\text{ kg} + 20\text{ kg} = 30\text{ kg}$.
Applying Newton's Second Law to the composite system:
$F = M \cdot a$ $600\text{ N} = 30\text{ kg} \cdot a$ $a = \frac{600}{30} = 20\text{ m/s}^2$Step 2: Free Body Diagram Analysis for Tension ($T$)
To find the tension $T$ in the string, we isolate body B ($m_2 = 20\text{ kg}$). The only horizontal force acting on body B is the tension $T$ exerted by the string [Per Newton's Third Law of Motion].
Applying Newton's Second Law to body B:
$T = m_2 \cdot a$Step 3: Solving for Tension
Substituting the known values into the equation derived in Step 2:
$T = 20\text{ kg} \times 20\text{ m/s}^2$ $T = 400\text{ N}$Summary of Dynamics
| Parameter | Value |
|---|---|
| Total Mass ($M$) | $30\text{ kg}$ |
| System Acceleration ($a$) | $20\text{ m/s}^2$ |
| Tension ($T$) | $400\text{ N}$ |
Final Solution: The tension in the string when the force is applied to the 10 kg mass is 400 N.
More Questions from Class 11 Physics Laws of Motion EXERCISES
- Q4.1(a): Give the magnitude and direction of the net force acting on a drop of rain falling down with a constant speed,
- Q4.1(b): Give the magnitude and direction of the net force acting on a cork of mass 10 g floating on water,
- Q4.1(c): Give the magnitude and direction of the net force acting on a kite skillfully held stationary in the sky,
- Q4.1(d): Give the magnitude and direction of the net force acting on a car moving with a constant velocity of 30 km/h on a rough road,
- Q4.1(e): Give the magnitude and direction of the net force acting on a high-speed electron in space far from all material objects, and free of electric and magnetic fields.
- Q4.10: A body of mass 0.40 kg moving initially with a constant speed of 10 (m s^{-1}) to the north is subject to a constant force of 8.0 N directed towards the south for 30 s. Take the instant the force is applied to be (t = 0), the position of the body at that time to be (x = 0), and predict its position at (t = -5) s, 25 s, 100 s.
- Q4.11(a): A truck starts from rest and accelerates uniformly at 2.0 (m s^{-2}). At (t = 10) s, a stone is dropped by a person standing on the top of the truck (6 m high from the ground). What are the velocity of the stone at (t = 11)s ? (Neglect air resistance.)
- Q4.11(b): A truck starts from rest and accelerates uniformly at 2.0 (m s^{-2}). At (t = 10) s, a stone is dropped by a person standing on the top of the truck (6 m high from the ground). What are the acceleration of the stone at (t = 11)s ? (Neglect air resistance.)
- Q4.12(a): A bob of mass 0.1 kg hung from the ceiling of a room by a string 2 m long is set into oscillation. The speed of the bob at its mean position is 1 (m s^{-1}). What is the trajectory of the bob if the string is cut when the bob is at one of its extreme positions,
- Q4.12(b): A bob of mass 0.1 kg hung from the ceiling of a room by a string 2 m long is set into oscillation. The speed of the bob at its mean position is 1 (m s^{-1}). What is the trajectory of the bob if the string is cut when the bob is at its mean position.
- Q4.13(a): A man of mass 70 kg stands on a weighing scale in a lift which is moving upwards with a uniform speed of 10 (m s^{-1}). What would be the readings on the scale in this case?
- Q4.13(b): A man of mass 70 kg stands on a weighing scale in a lift which is moving downwards with a uniform acceleration of 5 (m s^{-2}). What would be the readings on the scale in this case?
- Q4.13(c): A man of mass 70 kg stands on a weighing scale in a lift which is moving upwards with a uniform acceleration of 5 (m s^{-2}). What would be the readings on the scale in this case?
- Q4.13(d): A man of mass 70 kg stands on a weighing scale in a lift. What would be the reading if the lift mechanism failed and it hurtled down freely under gravity ?
- Q4.14(a): Figure 4.16 shows the position-time graph of a particle of mass 4 kg. What is the force on the particle for (t < 0), (t > 4) s, (0 < t < 4) s? (Consider one-dimensional motion only).
- Q4.14(b): Figure 4.16 shows the position-time graph of a particle of mass 4 kg. What is the impulse at (t = 0) and (t = 4) s ? (Consider one-dimensional motion only).
- Q4.15(i): Two bodies of masses 10 kg and 20 kg respectively kept on a smooth, horizontal surface are tied to the ends of a light string. A horizontal force (F = 600) N is applied to the 10 kg body (A) along the direction of string. What is the tension in the string?
- Q4.15(ii): Two bodies of masses 10 kg and 20 kg respectively kept on a smooth, horizontal surface are tied to the ends of a light string. A horizontal force (F = 600) N is applied to the 20 kg body (B) along the direction of string. What is the tension in the string?
- Q4.16: Two masses 8 kg and 12 kg are connected at the two ends of a light inextensible string that goes over a frictionless pulley. Find the acceleration of the masses, and the tension in the string when the masses are released.
- Q4.17: A nucleus is at rest in the laboratory frame of reference. Show that if it disintegrates into two smaller nuclei the products must move in opposite directions.
- Q4.18: Two billiard balls each of mass 0.05 kg moving in opposite directions with speed 6 (m s^{-1}) collide and rebound with the same speed. What is the impulse imparted to each ball due to the other ?
- Q4.19: A shell of mass 0.020 kg is fired by a gun of mass 100 kg. If the muzzle speed of the shell is 80 (m s^{-1}), what is the recoil speed of the gun ?
- Q4.2(a): A pebble of mass 0.05 kg is thrown vertically upwards. Give the direction and magnitude of the net force on the pebble, during its upward motion,
- Q4.2(b): A pebble of mass 0.05 kg is thrown vertically upwards. Give the direction and magnitude of the net force on the pebble, during its downward motion,
- Q4.2(c): A pebble of mass 0.05 kg is thrown vertically upwards. Give the direction and magnitude of the net force on the pebble, at the highest point where it is momentarily at rest. Do your answers change if the pebble was thrown at an angle of 45(^{\circ}) with the horizontal direction? Ignore air resistance.
- Q4.20: A batsman deflects a ball by an angle of 45(^{\circ}) without changing its initial speed which is equal to 54 km/h. What is the impulse imparted to the ball ? (Mass of the ball is 0.15 kg.)
- Q4.21: A stone of mass 0.25 kg tied to the end of a string is whirled round in a circle of radius 1.5 m with a speed of 40 rev./min in a horizontal plane. What is the tension in the string ? What is the maximum speed with which the stone can be whirled around if the string can withstand a maximum tension of 200 N ?
- Q4.22: If the speed of the stone is increased beyond the maximum permissible value, and the string breaks suddenly, which of the following correctly describes the trajectory of the stone after the string breaks :
- Q4.23(a): Explain why a horse cannot pull a cart and run in empty space,
- Q4.23(b): Explain why passengers are thrown forward from their seats when a speeding bus stops suddenly,
- Q4.23(c): Explain why it is easier to pull a lawn mower than to push it,
- Q4.23(d): Explain why a cricketer moves his hands backwards while holding a catch.
- Q4.3(a): Give the magnitude and direction of the net force acting on a stone of mass 0.1 kg, just after it is dropped from the window of a stationary train,
- Q4.3(b): Give the magnitude and direction of the net force acting on a stone of mass 0.1 kg, just after it is dropped from the window of a train running at a constant velocity of 36 km/h,
- Q4.3(c): Give the magnitude and direction of the net force acting on a stone of mass 0.1 kg, just after it is dropped from the window of a train accelerating with 1 (m s^{-2}),
- Q4.3(d): Give the magnitude and direction of the net force acting on a stone of mass 0.1 kg, lying on the floor of a train which is accelerating with 1 (m s^{-2}), the stone being at rest relative to the train. Neglect air resistance throughout.
- Q4.4: One end of a string of length (l) is connected to a particle of mass (m) and the other to a small peg on a smooth horizontal table. If the particle moves in a circle with speed (v) the net force on the particle (directed towards the centre) is : (T) is the tension in the string.
- Q4.5: A constant retarding force of 50 N is applied to a body of mass 20 kg moving initially with a speed of 15 (m s^{-1}). How long does the body take to stop ?
- Q4.6: A constant force acting on a body of mass 3.0 kg changes its speed from 2.0 (m s^{-1}) to 3.5 (m s^{-1}) in 25 s. The direction of the motion of the body remains unchanged. What is the magnitude and direction of the force ?
- Q4.7: A body of mass 5 kg is acted upon by two perpendicular forces 8 N and 6 N. Give the magnitude and direction of the acceleration of the body.
- Q4.8: The driver of a three-wheeler moving with a speed of 36 km/h sees a child standing in the middle of the road and brings his vehicle to rest in 4.0 s just in time to save the child. What is the average retarding force on the vehicle ? The mass of the three-wheeler is 400 kg and the mass of the driver is 65 kg.
- Q4.9: A rocket with a lift-off mass 20,000 kg is blasted upwards with an initial acceleration of 5.0 (m s^{-2}). Calculate the initial thrust (force) of the blast.
- Q5.1(a): Give the magnitude and direction of the net force acting on (a) a drop of rain falling down with a constant speed,
- Q5.1(b): Give the magnitude and direction of the net force acting on (b) a cork of mass 10 g floating on water,
- Q5.1(c): Give the magnitude and direction of the net force acting on (c) a kite skillfully held stationary in the sky,
- Q5.1(d): Give the magnitude and direction of the net force acting on (d) a car moving with a constant velocity of 30 km/h on a rough road,
- Q5.1(e): Give the magnitude and direction of the net force acting on (e) a high-speed electron in space far from all material objects, and free of electric and magnetic fields.
- Q5.10: A body of mass 0.40 kg moving initially with a constant speed of $10 m s^{-1}$ to the north is subject to a constant force of 8.0 N directed towards the south for 30 s. Take the instant the force is applied to be $t = 0$, the position of the body at that time to be $x = 0$, and predict its position at $t = –5 s$, $25 s$, $100 s$.
- Q5.11(a): A truck starts from rest and accelerates uniformly at $2.0 m s^{-2}$. At $t = 10 s$, a stone is dropped by a person standing on the top of the truck (6 m high from the ground). What are the (a) velocity of the stone at $t = 11s$ ? (Neglect air resistance.)
- Q5.11(b): A truck starts from rest and accelerates uniformly at $2.0 m s^{-2}$. At $t = 10 s$, a stone is dropped by a person standing on the top of the truck (6 m high from the ground). What are the (b) acceleration of the stone at $t = 11s$ ? (Neglect air resistance.)
- Q5.12(a): A bob of mass 0.1 kg hung from the ceiling of a room by a string 2 m long is set into oscillation. The speed of the bob at its mean position is $1 m s^{-1}$. What is the trajectory of the bob if the string is cut when the bob is (a) at one of its extreme positions,
- Q5.12(b): A bob of mass 0.1 kg hung from the ceiling of a room by a string 2 m long is set into oscillation. The speed of the bob at its mean position is $1 m s^{-1}$. What is the trajectory of the bob if the string is cut when the bob is (b) at its mean position.
- Q5.13(a): A man of mass 70 kg stands on a weighing scale in a lift which is moving (a) upwards with a uniform speed of $10 m s^{-1}$,
- Q5.13(b): A man of mass 70 kg stands on a weighing scale in a lift which is moving (b) downwards with a uniform acceleration of $5 m s^{-2}$,
- Q5.13(c): A man of mass 70 kg stands on a weighing scale in a lift which is moving (c) upwards with a uniform acceleration of $5 m s^{-2}$. What would be the readings on the scale in each case?
- Q5.13(d): A man of mass 70 kg stands on a weighing scale in a lift which is moving (d) What would be the reading if the lift mechanism failed and it hurtled down freely under gravity ?
- Q5.14(a): Figure 5.16 shows the position-time graph of a particle of mass 4 kg. What is the (a) force on the particle for $t < 0$, $t > 4 s$, $0 < t < 4 s$?
- Q5.14(b): Figure 5.16 shows the position-time graph of a particle of mass 4 kg. What is the (b) impulse at $t = 0$ and $t = 4 s$ ? (Consider one-dimensional motion only).
- Q5.15(ii): Two bodies of masses 10 kg and 20 kg respectively kept on a smooth, horizontal surface are tied to the ends of a light string. A horizontal force $F = 600 N$ is applied to (ii) B along the direction of string. What is the tension in the string in each case?
- Q5.16: Two masses 8 kg and 12 kg are connected at the two ends of a light inextensible string that goes over a frictionless pulley. Find the acceleration of the masses, and the tension in the string when the masses are released.
- Q5.17: A nucleus is at rest in the laboratory frame of reference. Show that if it disintegrates into two smaller nuclei the products must move in opposite directions.
- Q5.18: Two billiard balls each of mass 0.05 kg moving in opposite directions with speed $6 m s^{-1}$ collide and rebound with the same speed. What is the impulse imparted to each ball due to the other ?
- Q5.19: A shell of mass 0.020 kg is fired by a gun of mass 100 kg. If the muzzle speed of the shell is $80 m s^{-1}$, what is the recoil speed of the gun ?
- Q5.2(a): A pebble of mass 0.05 kg is thrown vertically upwards. Give the direction and magnitude of the net force on the pebble, (a) during its upward motion,
- Q5.2(b): A pebble of mass 0.05 kg is thrown vertically upwards. Give the direction and magnitude of the net force on the pebble, (b) during its downward motion,
- Q5.2(c): A pebble of mass 0.05 kg is thrown vertically upwards. Give the direction and magnitude of the net force on the pebble, (c) at the highest point where it is momentarily at rest. Do your answers change if the pebble was thrown at an angle of 45° with the horizontal direction? Ignore air resistance.
- Q5.20: A batsman deflects a ball by an angle of 45° without changing its initial speed which is equal to 54 km/h. What is the impulse imparted to the ball ? (Mass of the ball is 0.15 kg.)
- Q5.21: A stone of mass 0.25 kg tied to the end of a string is whirled round in a circle of radius 1.5 m with a speed of 40 rev./min in a horizontal plane. What is the tension in the string ? What is the maximum speed with which the stone can be whirled around if the string can withstand a maximum tension of 200 N ?
- Q5.22: If, A stone of mass 0.25 kg tied to the end of a string is whirled round in a circle of radius 1.5 m with a speed of 40 rev./min in a horizontal plane. What is the tension in the string ? What is the maximum speed with which the stone can be whirled around if the string can withstand a maximum tension of 200 N, the speed of the stone is increased beyond the maximum permissible value, and the string breaks suddenly, which of the following correctly describes the trajectory of the stone after the string breaks :
- Q5.23(a): Explain why (a) a horse cannot pull a cart and run in empty space,
- Q5.23(b): Explain why (b) passengers are thrown forward from their seats when a speeding bus stops suddenly,
- Q5.23(c): Explain why (c) it is easier to pull a lawn mower than to push it,
- Q5.23(d): Explain why (d) a cricketer moves his hands backwards while holding a catch.
- Q5.3(a): Give the magnitude and direction of the net force acting on a stone of mass 0.1 kg, (a) just after it is dropped from the window of a stationary train,
- Q5.3(b): Give the magnitude and direction of the net force acting on a stone of mass 0.1 kg, (b) just after it is dropped from the window of a train running at a constant velocity of 36 km/h,
- Q5.3(c): Give the magnitude and direction of the net force acting on a stone of mass 0.1 kg, (c) just after it is dropped from the window of a train accelerating with $1 m s^{-2}$,
- Q5.3(d): Give the magnitude and direction of the net force acting on a stone of mass 0.1 kg, (d) lying on the floor of a train which is accelerating with $1 m s^{-2}$, the stone being at rest relative to the train. Neglect air resistance throughout.
- Q5.4: One end of a string of length l is connected to a particle of mass m and the other to a small peg on a smooth horizontal table. If the particle moves in a circle with speed v the net force on the particle (directed towards the centre) is : $T$ is the tension in the string. [Choose the correct alternative].
- Q5.5: A constant retarding force of 50 N is applied to a body of mass 20 kg moving initially with a speed of $15 m s^{-1}$. How long does the body take to stop ?
- Q5.6: A constant force acting on a body of mass 3.0 kg changes its speed from $2.0 m s^{-1}$ to $3.5 m s^{-1}$ in 25 s. The direction of the motion of the body remains unchanged. What is the magnitude and direction of the force ?
- Q5.7: A body of mass 5 kg is acted upon by two perpendicular forces 8 N and 6 N. Give the magnitude and direction of the acceleration of the body.
- Q5.8: The driver of a three-wheeler moving with a speed of 36 km/h sees a child standing in the middle of the road and brings his vehicle to rest in 4.0 s just in time to save the child. What is the average retarding force on the vehicle ? The mass of the three-wheeler is 400 kg and the mass of the driver is 65 kg.
- Q5.9: A rocket with a lift-off mass 20,000 kg is blasted upwards with an initial acceleration of $5.0 m s^{-2}$. Calculate the initial thrust (force) of the blast.
CBSE Solutions for Class 11 Physics Laws of Motion
Chapters in CBSE - Class 11 Physics
Top Tutors who teach Laws of Motion
Top Tutor
Sector 39 Charmwood Village, Faridabad
6 yrs of
Exp
3 students
112 hrs of classes completed
500
per hour
Online Classes
In my experience providing tuition for Class 11 students, I aimed to create a supportive and engaging learning environment tailored to their unique needs. I focused on key subjects such as English, Social Studies which are crucial for their board examinations. Teaching Methodology: I began each session by assessing the students’ current understanding and identifying specific areas where they needed support. This allowed me to customize my lesson plans to address their weaknesses while reinforcing their strengths. I employed a variety of teaching methods, including: Interactive Discussions: I encouraged students to participate actively by asking questions and engaging in discussions around key concepts, which helped to deepen their understanding. Problem-Solving Sessions: In subjects like Mathematics and Science, I emphasized problem-solving techniques. I walked them through complex problems step-by-step, encouraging them to think critically and develop their reasoning skills. Practice Tests: I conducted regular quizzes and mock tests to familiarize them with the exam format and to track their progress. This also helped reduce anxiety leading up to their actual exams. Student Engagement: To keep students motivated, I incorporated real-life applications of the concepts we covered. For example, in Science, I would relate topics to everyday phenomena, making the material more relatable and interesting. I also encouraged peer collaboration, allowing students to work together on challenging problems, fostering teamwork and communication skills. Feedback and Support: I provided constructive feedback on their work, highlighting both areas of improvement and their successes. I made myself available for additional support outside of regular sessions, whether through email or online messaging, to answer questions and clarify doubts. Results and Impact: Many of my students showed significant improvement in their confidence and academic performance. Witnessing their growth, especially as they prepared for their board exams, was incredibly rewarding. I emphasized the importance of a positive mindset, helping them develop not just academically, but also personally. Overall, my experience teaching Class 11 tuition was fulfilling, as I was able to make a meaningful impact on my students' educational journeys while fostering a love for learning.
Satisfactory, command on subject. Very well described the topic it was just a demo class , rest depends on other topics, though I found mam is sweet n goo in her subject.
Top Tutor
Bandra West, Mumbai
15 yrs of
Exp
1 student
1 hrs of classes completed
700
per hour
Online Classes
Student's Home
Tutor's home
I have been teaching 11th Since 2014.
Top Tutor
HSR Layout, Bangalore
20 yrs of
Exp
32 students
1746 hrs of classes completed
600
per hour
Online Classes
Tutor's home
With a distinguished Doctorate in Chemistry, I bring 28 years of expertise, seamlessly integrating profound knowledge and unparalleled teaching prowess. As a Chemistry Teacher for CBSE and IBDP Chemistry Faculty, I've significantly contributed to intellectual growth in prestigious institutions like Kendriya Vidyalaya, Ecole Mondiale World School, and Singapore International School etc. Recognized as a trailblazer, I've served as an Assistant Examiner and Moderator for Internal Assessment in IBDP Chemistry for six years, upholding the highest evaluation standards and showcasing a deep understanding of curriculum intricacies. My extensive experiences beyond conventional teaching establish me as a luminary in Chemistry education, leaving an enduring legacy in the annals of education. I remain dedicated to inspiring future generations to achieve unparalleled heights in scientific inquiry and knowledge.
Dr. Anupa is a great teacher. She is patient and is interested in the learning and growth of the student.
Top Tutor
West Marredpally, Hyderabad
20 yrs of
Exp
1 student
127 hrs of classes completed
500
per hour
Online Classes
Student's Home
Tutor's home
I love to teach physics for classes 11th and 12th. Solve numericals and explain the concepts clearly to students. I emphasize understanding of the concepts clearly and then attempt solving ot numericals.
Super Tutor
Knowledge Park II, Noida
8 yrs of
Exp
352 students
65944 hrs of classes completed
400
per hour
Online Classes
I have been teaching students since past 8 years and in this journey many of them were able to crack their examination.My way of teaching makes approach towards the question more simpler and easier.If you feel jee is not yours cup of tea then trust me once I will make sure you will start feeling damn comfort and your way of thinking will definitely change Not just only education I teach my students about life values as cracking examination is combo of disciplne, determination,hardwordk and little luck so just doing solving any question never tends to success. All these qualities must get inbuilt.
Excellent classes. Sir is extremely enthusiastic and always ready to help. He provides all levels of notes and gives the freedom to students to choose. He is the super star teacher for physics and chemistry. Praying that tye enthusiasm persists. Thank you Sir.
