Available Answers

1. 1.

   Fig 2.26 shows the displacement-time graph for the motion of two boys and B along a straight road in the same direction.

   Answer the following :

   1. When did B start after A ?
   2. How far away was A from B when B started ?
   3. Which of the two has greater velocity ?
   4. When and where did B overtake A ?

   

2. 2.

   A car travels with a uniform velocity of 20 m s^-1 for 5 s. The brakes arc then applied and the car is uniformly retarded. It comes to rest in further 8 s. Draw a graph or velocity against time. Use this graph to find :

   1. the distance travelled in first 5 s.
   2. the distance travelled after the brakes are applied.
   3. total distance travelled, and
   4. acceleration during the first 5 s and last 8 s.

   The graph of velocity against time is shown in Fig. 2.27.

   

3. 3.

   A train starts from rest and accelerates uniformly at 100 m minute^-2 for 10 minutes. Find the velocity acquired by the train. It then maintains a constant velocity for 20 minutes. The brakes are then applied and the train is uniformly retarded. It comes to rest in 5 minutes. Draw a velocity-time graph and use it to find :

   1. the retardation in the last minutes.
   2. total distance travelled, and
   3. the average velocity or the train.
4. 4.

   A stone is thrown vertically upwards with an initial velocity of 40m s^-1.' Taking g= 10 m s^-2, draw the velocity-time graph the motion of stone till it comes back on the ground.

   1. Use graph to find the maximum height reached by the stone.
   2. What is the net displacement and total distance covered the stone?
5. 5.

   A car starling from rest, accelerates at a rate of 2 m s^-2 for 5 s. For this journey, (a) draw the velocity-time graph (b) draw the displacement-time graph using the velocity- time graph in part (a).

6. 6.

   The following table represents the velocity of a moving body at different instants of time.

   Time (s)	0	5	10	15	20	25	30
   Velocity (m s-1)	10	15	20	20	30	15	0

   Draw the velocity-time graph and answer the following :

   1. For which interval of time the has a uniform motion? Find the velocity in this time interval?
   2. For which interval of time the body has the accelerated motion? Calculate the acceleration.
   3. For which interval or time. the body has retardation Calculate the retardation.