Question

A car is sitting at a red light. When the light turns green, the driver hits the gas, giving the car a constant acceleration equal to 0.4 m/s². After the car has been accelerating for 0.8 seconds, what is its velocity equal to?

a) 0.32 m/s
b) 0.4 m/s
c) 0.64 m/s
d) 1.0 m/s

Answer 1

Using the basic kinematics equation (v = v0 + at), the car's velocity after accelerating for 0.8 seconds with a constant acceleration of 0.4 m/s^2 is found to be 0.32 m/s. The correct answer is option (a) 0.32 m/s.

Step-by-step explanation:

To determine the velocity of the car after accelerating for 0.8 seconds, we can use the basic kinematic equation for acceleration, which states that the final velocity (v) is equal to the initial velocity (v0) plus the acceleration (a) multiplied by the time (t), which can be written as:

v = v0 + at

Since the car is initially at rest, the initial velocity v0 is 0 m/s. We are given an acceleration (a) of 0.4 m/s2 and a time (t) of 0.8 seconds. Substituting these values into the equation we get:

v = 0 m/s + (0.4 m/s2 × 0.8 s)

So, the final velocity (v) after 0.8 seconds is:

v = 0.32 m/s

Therefore, the correct answer to the student's question is option (a) 0.32 m/s.