Answer:80 Watts
Explanation:To calculate the power exerted on the cart, you can use the formula:
Power = Force × Velocity
Given:
Force = 20 N
Velocity = 4 m/s
So, plugging in the values:
Power = 20 N × 4 m/s = 80 Watts
Therefore, the power exerted on the cart when it reaches a speed of 4 m/s is 80 Watts.