Science Spectrum

Two boxes, P and Q, resting on a rough horizontal surface, are connected by a light inextensible string. The boxes have masses 5 kg and 2 kg respectively. A constant force F, acting at an angle of 30° to the horizontal, is applied to the 5 kg box, as shown below.

The two boxes now move to the right at a constant speed of   2 m∙s⁻¹.

Box P experiences a constant frictional force of 5 N and box Q a constant frictional force of 3 N.

1. Draw a labelled free-body diagram for box Q. (4)

2. Calculate the magnitude of force F. (6)