A car travels in a straight line for 4 h at a constant speed of 63 km/h.

What is its acceleration?
Answer in units of m/s^2?

a = 0 (constant velocity)

Extra credit: why does it matter that it moved in a straight line?

To find the acceleration, we need to use the formula:

Acceleration = (Final Velocity - Initial Velocity) / Time

In this case, the car is traveling in a straight line at a constant speed of 63 km/h, which means the initial velocity is also 63 km/h.

First, we need to convert the initial velocity from km/h to m/s. To do this, we can use the conversion factor: 1 km/h = 0.2778 m/s.

So, the initial velocity in m/s = 63 km/h * 0.2778 m/s = 17.5 m/s.

Since the car is moving at a constant speed, its final velocity will also be 17.5 m/s.

The time taken by the car is given as 4 hours, which needs to be converted to seconds. There are 3600 seconds in 1 hour.

So, the time in seconds = 4 hours * 3600 seconds/hour = 14,400 seconds.

Now we can calculate the acceleration:

Acceleration = (Final Velocity - Initial Velocity) / Time
= (17.5 m/s - 17.5 m/s) / 14,400 s
= 0 m/s^2

Therefore, the acceleration of the car is 0 m/s^2.