Question

Use the graph above to determine the change in speed of the object between 20 and 30 seconds?

Answer 1

Answer:

6 m/s

Explanation:

To determine the change in speed of the object, we just need to determine its speed at t = 30 s and at t = 20 s, and then calculate the difference.

The speed at t = 30 is:

v = 6 m/s

While the speed at t = 20 s is:

u = 0

Therefore, the change in speed is:

$\Delta v = v-u=6-0 = 6 m/s$

Answer 2

Explanation:

The attached figure shows the acceleration time graph of an object. We known that the slope of the a-t graph gives the velocity of an object. The area under the a-t graph gives the velocity of object.

In x axis, time t = 30 s- 20 s = 10 s

In y axis, acceleration, $a = 6 - 0=6\ m/s^2$

Area under the graph from 20 to 30 seconds is given by :

$A=v=\dfrac{1}{2}\times 10\times 6$

v = 30 m/s

So, the change in speed of the object is 30 m/s. Hence, this is the required solution.