1. Find the unbalanced force required to accelerate a 6kg mass at 3ms^-2.

2. Find the acceleration of a 200kg rock, rolling down a hill, if the unbalanced force acting on it is 1kN.

3. What is the mass of a trolley if an unbalanced force of 12N causes it to accelerate at 4ms^-2?

4. The forces acting on a car of mass 1000kg are shown below.

(a) Find the unbalanced force acting on the car.

(b) Calculate the acceleration of the car.

5. A model motor boat of mass 4 kg is initially at rest on a pond. The boat’s motor, which provides a constant force of 5 N, is switched on. As the boat accelerates, the force of friction acting on it increases. A graph of the force of friction acting on the boat against time is shown.

 

(a)

(i) State the force of friction acting on the boat 2 s after the motor is switched on.

(ii) Calculate the acceleration of the boat at this time.

(iii) Describe and explain the movement of the boat after 7 s.

 

6. Stephen and Jack are invited along to ‘Techno toys’ workshop to try out a new remote control car. They line the car up to race along the 200 m track and then start it off.

(a) Describe how the designers could work out the car’s instantaneous speed as it goes round the corner of the track. Your answer must include:

– any apparatus they would need
– any measurements they would take
– any calculations they would do.

 

The speed time graph below represents the motion of the car during part of the race.

(b) Calculate the acceleration of the car during the first 6 seconds.

(c) How far did the car travel during the 18 seconds represented by the graph.

(d) During the period 6 s to 14 s the car exerted an engine force of 450 N. What size are the frictional forces acting on the car at this time.

(e) How could the designers reduce the frictional forces acting on the car.

(f) Draw the graph that would have been produced if the race had taken place on a wet day.