A car travels in a straight line for 5.4 h at a

constant speed of 79 km/h .
What is its acceleration?
Answer in units of m/s2.

constant speed is zero acceleration.

A car, moving along a straight stretch of high- way, begins to accelerate at 0.0121 m/s2. It takes the car 66.5 s to cover 1 km.

How fast was the car going when it first began to accelerate?
Answer in units of m/s.

Acceleration is the rate of change of velocity over time. Since the car travels at a constant speed, its velocity does not change and therefore its acceleration is zero. Thus, the acceleration of the car is 0 m/s².

Acceleration is the rate at which an object changes its velocity. It is given by the equation:

acceleration = (final velocity - initial velocity) / time

In this case, the car is traveling at a constant speed of 79 km/h for 5.4 hours. Since the car is traveling at a constant speed, its final velocity is the same as its initial velocity, and therefore the change in velocity is 0 km/h.

To find the acceleration, we need to convert the units to meters per second (m/s). 1 km/h is equal to 1000/3600 m/s, so 79 km/h is equal to (79 * 1000) / 3600 m/s.

Now we can calculate the acceleration:

acceleration = (0 m/s - (79 * 1000 / 3600) m/s) / (5.4 h)

Simplifying the equation, we can calculate the acceleration:

acceleration = - (79 * 1000) / (3600 * 5.4) m/s²

Evaluating the expression, we find that the acceleration is approximately -4.53 m/s².

Therefore, the acceleration of the car is -4.53 m/s².