# FORCES

Use these questions to help you revise to see the answers move you mouse over the hidden text in the answer box

 QUESTIONS ANSWER BOX 1. Pushing, pulling, twisting and squeezing are all examples of _________ Forces. 2. Force meters measure the size of a force in _______ Newtons. 3. Forces can change the size or s______ of an object. They shape, speed direction. can change the sp_____ of an object, or change the d_______ of a moving object. 4. What do we call the force when two things rub friction together? 5. How can the force from question 4 be made smaller? Lubrication. (make the things slippery with oil or grease). 6. Why do things have weight? Because of the pull of gravity 7. What do we call things that have little air Streamlined. resistance? 8. When something floats, the upthrust is equal to its balanced weight. The two forces are b 9. A boat floats higher in sea water than in fresh water. Sea water is denser (so a smaller volume of Why? water needs to be displaced in order to give the same upthrust. 10. What do we call a lever that lifts a large load, using A force magnifier. a smaller effort? 11. Give an example of a lever used as a distance magnifier. Your arm, the hand on a clock, a pedal bin. 12. Besides a lever, what other machine can make lifting A pulley. easier? 13. You push something with a force of 5N and the force 5N-2N=3N of friction is 2N. What is the resultant force? 14. If a push force is equal to the friction force, what can It does not move (or if it's moving already, you say about the movement of an object? it keeps moving at the same speed). 15. An athlete runs 50 m in 5 seconds. What is the athletes 50m / 15s = 10 m/s average speed during the race? 16. If two children, each weighing 20 kg, sit on a see-saw, Force x Distance = Moment 3m from the pivot, how far from the pivot must Dad who (20 kg + 20 kg) x 3m = 120 weighs 60 kg sit? 60 kgx 2m = 120 Answer = 2 metres