You may use the value g (earth) = 10ms^{-2} and g (moon) = 1.62 ms^{-2}.

**1.** State Newton’s three laws of motion. In the context of these laws, explain a) why it is a good idea to wear a seat belt and b) it requires more force to change the direction of a bus than a mini.

**2.**Distinguish between mass and weight stating the units used for each.

What is the weight of a body with mass 20kg?

What would the same body weigh on the moon?

**3.**a) Draw a diagram showing the forces acting on a spherical body resting on a rough inclined plane, identifying the weight, reaction and frictional force.

b)If a force is applied upwards along the plane, show the direction of the frictional force if (a) the body is about to slide down the plane and (b) the body is about to slide up the plane.

**4.**If F_{1} = 80N, find the other forces.

**5.**A picture is hanging symmetrically by two strings on a wall as shown below. The picture weighs 15kg. Find the tension in the two strings (assume the tension is the same in each string).

**6.**A body with mass 50kg is resting on a rough horizontal plane. The coefficient of friction is 0.6. If a horizontal force of 200N is applied, will the body move? If a force of 800N is applied, what will be the acceleration of the body?

If this rough plane is now tilted at an angle of 30°, find the acceleration of the same box with an applied force of 800N parallel and upwards to the slope.

Draw diagrams to illustrate your answer.

**7.**By showing the forces in the cable, show how a simple pulley is used to lift a load. Investigate how pulley systems can be used to increase the load that can be lifted with a given force.

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