Question

The Nardo ring is a circular test track for cars. It has a circumference of 12.5 km. Cars travel around the track at a constant speed of 100 km/h. A car starts at the easternmost point of the ring and drives for 30 minutes at this speed.
Required:
a. What distance, in km, does the car travel?
b. What is the magnitude of the car's displacement, in km, from its initial position?
c. What is the speed of the car in m/s?

Answer 1

Answer: 50 km, 0, 27.78 m/s

Explanation:

Given

Circumference of the track is $12.5\ km$

Speed of car is $100\ km/h$

Car drives for $30\ \text{minute}\ or\ 0.5\ hr$

(a)Distance traveled is

$\Rightarrow D=100\times 0.5\\\Rightarrow D=50\ km$

(b)displacement of the car

It can be observed that 12.5 is a multiple of 50, that is, 50 km can be interpreted as 4 complete rounds of the track.

Therefore, the displacement of the car is zero.

(c)To convert kmph to m/s, multiply the entity by $\frac{5}{18}$

$\Rightarrow 100\times \dfrac{5}{18}\\\\\Rightarrow 27.78\ m/s$