# Question 3

A 4 kg block is pulled up along a frictionless incline by a constant force F acting parallel  to the incline, as shown below. The incline makes an angle of 30° with the horizontal. The block moves at CONSTANT VELOCITY.

3.1 State Newton’s First Law of Motion in words. (2)

3.2 Draw a labelled free-body diagram showing all the forces acting on the block. (3)

3.3 Calculate the magnitude of:

3.3.1 The perpendicular component of the weight of the block (3)

3.3.2 Force F (3)

The same block is now pulled up along a rough incline by a constant force of 25 N   acting parallel to the incline, as shown below. The incline makes an angle of 30° with the horizontal.

The acceleration of the block is now 0,2 m·s-2 upwards along the incline.

3.4 Calculate the:

3.4.1 Magnitude of the kinetic frictional force acting on the block (4)

3.4.2 Coefficient of kinetic friction between the block and the surface of the incline (3)

The force of 25 N acting on the block on the rough incline is now removed, as shown
below.

3.5 How will EACH of the following quantities change in MAGNITUDE and DIRECTION?

3.5.1 Weight of the block (2)

3.5.2 Acceleration of the block (2)

3.5.3 Kinetic frictional force acting on the block (2)

[24]