# Mechanics

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a driver of a 1200-kg car notices that the car slows from 20 m/s to 15 m/s as it coasts a distance of 130 m along level ground. How large a force opposes the motion? Show the solution

• Mechanics -

Given:
m = 1200kg
u = 20m/s
v = 15m/s
s = 130m
Use:
v = u + at
s = ut + (at^2)/2
F = ma

Solve the velocity equation for time (t).

Substitute this into the displacement equation to solve for acceleration (a).

Multiply acceleration by mass (m) to give force (F).

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