Science Updates

(a) rolling, static, sliding

(b) rolling, sliding, static

(c) static, sliding, rolling

(d) sliding, static, rolling read less

When an object starts moving from the state of rest, it is called static friction.

The force required to keep the object moving with the same speed is called sliding friction.

When the box starts sliding, the contact points on its surface do not get enough time to lock into the contact points on the floor. So sliding friction is less than static friction.

Name three liquids, which when tested in the manner shown in Fig. 14.9, may cause the magnetic needle to deflect?

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The bulb does not glow in the setup shown in Fig. 14.10. List the possible reasons. Explain your answer?

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If the current through the circuit is weak, then the filament does not get heated sufficiently, and it does not glow. Though the material may conduct efficiently, it may not conduct as a metal. As a result, even though the circuit is complete, it may not get sufficient current to glow. The solution is non conducting.