A toy car with a mass of 5.5 kg is moving horizontally over flat ground at a speed of 2.1 m/s. An unknown force then directly pushes the car for a distance of 3 meters, after which the car has a speed of 7.3 m/s. You may assume that air resistance and friction are both negligible. What was the magnitude of the unknown force

The magnitude of the unknown force is 44.8 N.

Explanation:

The force can be found with Newton's second law:                

Where:

m: is the mass of the toy car = 5.5 kg

a: is the acceleration

F: is the force =?

We can calculate the acceleration with the following kinematic equation:

Where:

: is the final speed = 7.3 m/s

: is the initial speed = 2.1 m/s

d: is the distance traveled = 3 m

Hence, the acceleration is:

Finally, the magnitude of the force is:

Therefore, the magnitude of the unknown force is 44.8 N.

I hope it helps you!                                

0.11 m/s and 0.28 m/s should be correct

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