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## Homework Statement

A motorcycle and 60.0 kg rider accelerate at 3.0 m/s^2 up a ramp inclined 10 degrees above the horizontal. (a) What is the magnitude of the

*net*force acting on the rider? (b) What is the magnitude of the force on the rider from the motorcycle?

## Homework Equations

Net Force = Mass x Acceleration

Answer given for first part: 180 N

Answer given for second part: 640 N

## The Attempt at a Solution

The first part is easily solved: Since the mass is given to be 60 kg, and the acceleration up the incline is 3 m/s^2, therefore the

*net*force is 60 x 3 = 180 N. This matches the answer given.

For the second part, I thought it could be done by taking the normal force acting on the motorcycle, which on the given incline, would be = mg cos 10 degrees = 60 x 9.8 x cos 10 degrees = 579 N.

This is way off the answer given, which is 640 N. Did I get some theoretical bit wrong? I really don't see any other force which should be acting - after all, the mass of the motorcycle is not given.