Question 2

2.1 An 8 kg block, P, is being pulled by constant force F up a rough inclined plane at an angle of 30^o to the horizontal, at CONSTANT SPEED.

Force F is parallel to the inclined plane, as shown in the diagram below.

2.1.1 State Newton’s First Law in words. (2)

2.1.2 Draw a labelled free-body diagram for block P. (4)

The kinetic frictional force between the block and the surface of the inclined plane is 20,37 N.

2.1.3 Calculate the magnitude of force F. (5)

Force F is now removed and the block ACCELERATES down the plane.
The kinetic frictional force remains 20,37 N.

2.1.4 Calculate the magnitude of the acceleration of the block. (4)

2.2 A 200 kg rock lies on the surface of a planet. The acceleration due to gravity on the surface of the planet is 6,0 m·s^-2.

2.2.1 State Newton’s Law of Universal Gravitation in words. (2)

2.2.2 Calculate the mass of the planet if its radius is 700 km. (4)

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