Question

20. What is the difference between uniform linear motion and uniform circular motion ? Explain
21. State an important characteristic of uniform circular motion. Name the force which brings about uniform
circular motion.
22. Find the initial velocity of a car which is stopped in 10 seconds by applying brakes. The retardation due to
brakes is 2.5 m/s2
79 Describe the motion of a body which is accelerating at a constant rate of 10 m 52. If the body starts from rest.​

Answer 1

Answer:

20) In uniform linear motion, the speed and direction of motion is fixed and so, it is not accelerated. Example- A car running on a straight road. In uniform circular motion, the speed is constant but the direction of motion changes continuously and hence, it is accelerated. Example- Motion of earth around the sun.

21) An important characteristic of uniform circular motion is that the direction of motion in it changes continuously with time, so it is accelerated.

Centripetal force brings about uniform circular motion.

22) Initial velocity, u=?

Final velocity, v=0m/s (car is stopped)

Acceleration, a=−2.5m/s

2

(negative because it is retardation)

Time, t=10s

Use the relation of the first equation of motion:

v=u+at

0=u+(−2.5)×10

u=25m/s

79) The velocity of this body is increasing at a rate of '10 metres per second'. every second.

Initial velocity, u=0m/s

Time, t=2s

Acceleration, a=10m/s

2

Using the second equation of motion,

s=ut+

2

1

at

2

=0×2+

2

1

×10×2×2

=0+20=20m