A car travels anticlockwise along a horizontal circular road of radius 12 m, as shown.
The car takes a time of 4.0 s to move from position P to position Q.
What is the magnitude of the average velocity of the car for the journey from P to Q?
A 4.2 m s–1
B 4.7 m s–1
C 6.0 m s–1
D 14 m s–1
ANSWER: A
The Physics Behind
- Average velocity v of an object that has moved a displacement d in time t is
v = d / t
- The time t is given [4.0 s]. The displacement d however needs to be calculated first and this is the straight line distance from P to Q.
- You should see that you can have a right triangle with the sides measuring 12 m each.
- The hypotenuse is the d. Using Pythagorean Theorem you should get d = 17 m.
- For the v, divide 17 m by 4.0 s.
- The answer therefore is A.
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