Question

11. The speed-time graph for a car is shown is Fig. 22
(a) Find how far does the car travel in the first 4
seconds. Shade the area on the graph that
represents the distance travelled by the car
during the period. (b) Which part of the graph
represents uniform motion of the car?
​

Answer 1

Explanation:

The total number of divisions on horizontal axis for 2 s is 5.

The total number of divisions on vertical axis for 2 m/s is 3.

The total displacement of the car during these two seconds will be given as the area under all these squares.

The area under the (3×5) squares is given as:

A

15

=2×2 = 4

So, the area under one small square is :

A

1

=

15

4

Now, the area under the graph for 4 sec is:

the number of squares under the graph is :

n=57 small squares + 6 half small squares

So, total number of squares =60.

So, the distance traveled by the car is the area under the curve.

S=60×

15

4

S=16 m

(b)

The car moves under the uniform motion after the instant t=6 s because after this instant, the speed of the car becomes constant.