Question

A car with a mass of 1200 kg is on a hill that is inclined at 18 degrees. What must be the force of friction present to keep it at rest? Draw the free body diagram and show all forces present. Find the net external force. Please show all your work.

Answer 1

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There are two forces acting upon the skydiver - gravity (down) and air resistance (up).

 The force of gravity has a magnitude of m•g = (72 kg) •(9.8 m/s/s) = 706 N

The sum of the vertical forces is

∑Fy = 540 N, up + 706 N

down = 166 N, down

The acceleration of the skydiver can be computed using the equation

 ∑Fy = m•ay.

ay = (166 N, down) / (72 kg) = 2.3 m/s/s, down