Question: A car of mass 1000 kg is moving with a velocity of 20 m/s. The car is subject to a constant force of 5000 N applied in the opposite direction of motion. Calculate the acceleration of the car and the time it will take to stop completely.

Solution:

Given: Mass of the car, m = 1000 kg Initial velocity, v = 20 m/s Force applied, F = 5000 N

Using Newton's second law of motion, we can relate the force, mass, and acceleration as follows: F = ma

First, we need to find the acceleration (a). Rearranging the equation, we get: a = F / m

Substituting the given values, we have: a = 5000 N / 1000 kg

Let's calculate the acceleration: a = 5 m/s²

Now, let's find how long it will take for the car to stop completely. We can use the equation of motion: v = u + at

Since the final velocity is 0 m/s when the car stops, the equation becomes: 0 = 20 m/s + (-5 m/s²) * t

Rearranging the equation, we find: 5t = 20

Let's solve the equation for t: t = 4 s

Therefore, the car will accelerate at 5 m/s² and it will take 4 seconds for the car to stop completely.