## Motion NCERT Problems with Solutions- Part 2

**Motion is a very important topic of Physics. Here are Motion NCERT Problems with Solutions for your practice**

### Problem 1. A motorboat starting from rest on a lake accelerates in a straight line at a constant rate of 3.0 m s^{-2} for 8.0 s . How far does the boat travel during this time?

**Answer.**

### Problem 2. Fig. shows the distance-time graph of three objects A, B and C. Study the graph and answer the following questions:

#### Which of the three is traveling the fastest?

#### Are all three ever at the same point on the road?

#### How far has C traveled when B passes A?

#### How far has B traveled by the time it passes C?

** **

(ii) No, all three do not meet at any point on the road,

(iii) When B passes A at point N (at 1.2 hours), C is at a distance of approximately 8 km from

the origin O.

(iv) B passes C at 0.7 hours. During this time B covers distance of 6 km.

### Problem 3. A ball is gently dropped from a height of 20 m. If its velocity increases uniformly at the rate of 10 ms^{-2}, with what velocity will it strike the ground? After what time will it strike the ground?

**Answer.**

### Problem 4. The speed-time graph for a car is shown is Fig.

#### (a) Find how far does the car travel in the first 4 seconds. Shade the area on the graph that represents the distance traveled by the car during the period.

#### (b) Which part of the graph represents uniform motion of the car?

** **

**Answer.**

(a) On horizontal axis, 5 small divisions = 2 s On vertical axis, 3 small divisions = 2 m/s

= 2 s x 2 m/s = 4m

**Area of 1 small square =4/15m**

Total area under the speed-time graph from time 0 to 4 s

= 57 small squares + 1/2 x 6 small squares

= 60 small square

Distance traveled by the car in first 4 seconds

= Area under the speed-time graph from 0 to 4 s

= 60 small squares

= 60 x 4/15 m

= 16 meter.

(b) After 6 s, the car has a uniform motion for straight part of graph BC.

### Problem 5. State which of the following situations are possible and give an example for each of these:

#### (a) an object with a constant acceleration but with zero velocity.

#### (b) an object moving in a certain direction with an acceleration in the perpendicular direction.

**Answer.**

(a) Yes, a body can have acceleration even if its velocity is zero. When a body is thrown

up, at highest point its velocity is zero but it has acceleration equal to acceleration due to gravity.

(b) Yes, when an object moves on a circular path, it has centripetal acceleration which is perpendicular to displacement.

### Problem 6. An artificial satellite is moving in a circular orbit of radius 42250 km. Calculate its speed if it takes 24 hours to revolve around the earth.

**Answer.**