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 :
- When did B start after A ?
- How far away was A from B when B started ?
- Which of the two has greater velocity ?
- When and where did B overtake A ?
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 :
- the distance travelled in first 5 s.
- the distance travelled after the brakes are applied.
- total distance travelled, and
- acceleration during the first 5 s and last 8 s.
The graph of velocity against time is shown in Fig. 2.27.
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 :
- the retardation in the last minutes.
- total distance travelled, and
- the average velocity or the train.
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.
- Use graph to find the maximum height reached by the stone.
- What is the net displacement and total distance covered the stone?
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).