Everything Science Grade 10

21.6 CHAPTER 21. MOTION IN ONE DIMENSION

A brief description of the motion of the object could read something

like this: Att= 0s and object is stationary at some position and remains

stationary untilt= 2s when it begins accelerating. It accelerates in

a positive direction for 2 seconds untilt= 4s and then travels at a

constant velocity for a further 2 seconds.

Example 4: Calculations from a velocity vs. time graph

QUESTION

The velocity vs. time graph of a truck is plotted below. Calculate the distance and

displacement of the truck after 15 seconds.

0

1

2

3

4

− 1

− 2

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

~v(m·s−^1 )

t(s)

SOLUTION

Step 1:Decide how to tackle the problem

We are asked to calculate the distance and displacement of the car.

All we need to remember here is that we can use the area between the

velocity vs. time graph and the time axis to determine the distance and

displacement.

Step 2:Determine the area under the velocity vs. time graph

Break the motion up: 0 – 5 seconds, 5 – 12 seconds, 12 – 14 seconds

and 14 – 15 seconds.

420 Physics: Mechanics