Pupil sheet · Resultant force
Resultant force — return questions
Name ______________________ Date ____________
Use one to two weeks after the lessons. Keep the notes and the lesson closed.
1. state / determine / describe
Answer from memory. (a) State what is meant by the resultant force on an object. (b) A box is pushed to the right with 45 N. Two forces act on it to the left: 30 N and 15 N. Determine the resultant force on the box. (c) A pupil pushes a heavy cupboard to the right with 120 N, but it stays still. State the resultant force on the cupboard. Then determine the size and direction of the other horizontal force on it. (d) State the two ways in which a resultant force can change the velocity of an object. (e) A skater glides east across smooth ice. A steady wind then pushes on her. Describe what happens to her motion if the wind pushes (i) towards the west, (ii) towards the north.
(a) The resultant force
(b) The box
(c) The cupboard
(d) Two ways
(e) The skater: (i) west, (ii) north
2. explain / determine / state / give / calculate
Supplement. Answer from memory. (a) Explain why weight is a vector but mass is not. (b) A toy boat moves at 1.6 m/s towards the north through the water, and a stream carries the water east at 0.90 m/s. Ana finds the resultant velocity by scale drawing, with 1 cm = 0.20 m/s. Determine the length of the arrow she must draw for 1.6 m/s. Her resultant arrow measures 9.2 cm: determine the size of the resultant velocity. (c) State the equation that links resultant force, mass and acceleration, and give the unit of each quantity. (d) A resultant force of 0.45 N towards the north gives a toy cart an acceleration of 1.5 m/s². Calculate the mass of the cart, and state the direction of its acceleration. (e) A puck goes round in a circle on a string at a steady speed. The pull of the string is then increased. State what happens (i) to the speed, if the radius stays the same; (ii) to the radius, if the speed stays the same.
(a) Weight and mass
(b) The toy boat: arrow and resultant
(c) The equation
(d) The cart’s mass
(e) The circle: (i) speed, (ii) radius