Question

a car of mass 100 kg is at rest. After 10 seconds of it starts,the car is moving with a velocity of 2i+ 3j m/s. calculate the force on the car.
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Answer 1

Explanation:

The car of mass m is moving in the horizontal direction with acceleration a.

However, the normal reaction acts on the car from the ground and in the vertical direction.

Now, we know that work done is given as dot product of force and displacement.

W = F · s = Fscosθ

Now, the angle between the displacement and the force of normal reaction is θ = 90°.

Therefore, work done is zero. W = Fscos90 = 0