Question

A car moves in a straight line at 20.0 m/s for 12.0 miles, then at 30.0 m/s for another 12.0 miles.

(a) Is the car's average speed less than, greater than, or equal to 25.0 m/s?
less than 25.0 m/s
equal to 25.0 m/s
greater than 25.0 m/s

(b) Calculate the car's average speed. (Enter your answer to three significant figures.)

Answer 1

What is the question being asked

Answer 2

(a). The average speed less than 25.0 m/s.

(b). The car's average speed is 24 m/s.

Step-by-step explanation:

Given that,

Speed v= 20.0 m/s

Distance d= 12.0 miles

Speed v'= 30.0 m/s

Distance d'=12.0 miles

We need to calculate the time for first 12 miles distance

Using formula of time

`v=(d)/(t)`

`t = (d)/(v)`

`t=(12.0)/(20.0)`

`t=0.6\ sec`

We need to calculate the time for another 12 miles distance

Using formula of time

`t=(12.0)/(30.0)`

`t=0.4\ sec`

We need to calculate the average speed

`v_(avg)=(D)/(T)`

Where, D = total distance

T = total time

Put the value into the formula

`v_(avg)=(12.0+12.0)/(0.6+0.4)`

`v_(avg)=(24.0)/(1.0)`

`v_(avg)=24\ m/s`

The average speed less than 25.0 m/s.

(b). The car's average speed is 24 m/s.

Hence, This is the required solution.