Pearson Edexcel International GCSE (9–1) · PHYSICS · Unit
Forces and Motion
367 practice questions
Topics covered
Practice questions
161–170 of 181 · Normal
Question 161
4 marks · Normal
Answer and see the solution →A uniform plank of wood is 4.0 m long and has a weight of 200 N. It rests horizontally on two supports placed 0.5 m from each end.
Wooden plank supported near each end (a)[1 mark]Calculate the distance from Support 1 to the centre of gravity of the plank.
(b)[3 marks]Determine, using the principle of moments about Support 1, the upward force at Support 2.
Question 162
2 marks · Normal
Answer and see the solution →Explain why it is easier to loosen a tight bolt using a spanner with a long handle rather than a short one.
Question 163
4 marks · Normal
Answer and see the solution →A mechanic uses a wrench to loosen a bolt. The wrench is 0.30 m long, and he applies a force of 150 N perpendicular to the wrench at its end.
(a)[2 marks]Calculate the moment produced by the mechanic about the centre of the bolt.
(b)[2 marks]Explain what would happen to the moment if the mechanic applied the same force closer to the centre of the bolt.
Question 164
2 marks · Normal
Answer and see the solution →State what is meant by the 'centre of gravity' of a body, and describe how the weight of a body acts with respect to this point.
Question 165
4 marks · Normal
Answer and see the solution →A uniform horizontal rod of length 1.8 m and weight 90 N is supported at its two ends, labelled P and Q. A load of 60 N is hung from the rod, 0.3 m from end P.
(a)[3 marks]Taking moments about point P, calculate the upward force at Q.
(b)[1 mark]State the upward force at P.
Question 166
2 marks · Normal
Answer and see the solution →Diagram Force (N) Distance from pivot (m) Angle to lever arm (°) A 40 0.2 90 B 60 0.1 0 C 80 0.05 90 D 100 0.01 90 Look at the table showing different forces applied to a door at various distances and angles from the hinge (pivot).
Question 167
3 marks · Normal
Answer and see the solution →A bridge is supported at both ends. A heavy truck stops near the left end of the bridge. Explain, using the principle of moments, how the upward forces at the left and right supports change as the truck moves from the left end to the centre of the bridge.
Question 168
6 marks · Normal
Answer and see the solution →A 2.0 m long uniform beam of mass 8.0 kg is supported at each end. A box of mass 12 kg is placed 1.2 m from one end of the beam.
(a)[2 marks]Calculate the weight of the beam and the weight of the box. Give your answers in newtons (N). (Take .)
(b)[1 mark]Find the total downward force acting on the supports.
(c)[3 marks]Calculate the upward force on the support that is closest to the box. Show your working.
Question 169
5 marks · Normal
Answer and see the solution →A spring has an unstretched length of 7.0 cm. The table below shows how the length of the spring changes as different forces are applied.
Force and length data for a spring Force (N) Length (cm) 0 7.0 2 7.5 4 8.1 6 8.7 8 9.2 (a)[1 mark]Complete the following column to show the extension of the spring for each force.
Force (N) Extension (cm) 0 2 4 6 8 (b)[2 marks]Plot a graph of force (y-axis) against extension (x-axis). (Describe the shape of the graph.)
(c)[2 marks]Does this spring obey Hooke’s law over the range of forces shown? Explain your answer.
Question 170
5 marks · Normal
Answer and see the solution →A 1500 kg car is travelling at 18 m/s when the driver sees a hazard and reacts, then brakes to a stop.
(a)[1 mark]Calculate the momentum of the car before the driver reacts.
(b)[2 marks]If the driver’s reaction time is 0.6 s, calculate the thinking distance (distance travelled during reaction).
(c)[2 marks]After braking, the car stops in 5.0 s. Calculate the average braking force acting on the car (assume constant deceleration).