1. Year 7 Science Forces

4. What is a Force? A force is a push or a pull. D i f f e r e n t types of forces can act on a object at the same time. Forces can act in different directions. An object can change speed or direction only when the forces acting on it are unbalanced. Action forces in one direction cause re action forces in the other direction.

5. Different types of forces can act on an object at the same time and in different directions… Objects speed up/slow down when the forces are balanced or unbalanced?

6. Forces A force cannot be seen! It has no shape, colour or smell They are interactions between objects The effects of forces can be seen If an object is speeding up, slowing down or changing direction there are unbalanced forces acting on it!

7. Sir Isaac Newton (1642-1727). Millions saw the apple fall, but Newton asked why.

8. Measuring Forces The units of force: the Newton (N) 1 N is the equivalent of 98g weight Or 1 kg is 9.8N

9. Forces Forces Represented by vectors (drawn as arrows) This is a vector of size 20N to the 20Nright 20N20N to the left 5N5N up

10. Forces

11. Forces Forces actingResultant Force 20N 30N 50N 20N No resultant force BALANCED forces 20N 60N 50N 10N This means that while forces are acting, they effectively ‘cancel’ each other out

12. Everyday Forces What is a force? ◦ A force is a push or a pull. Can you name any forces?

13. What forces are present?

14. Contact and Non-Contact Forces Some forces are touching or contact forces. ◦ Physical push/pull ◦ Wind (air) ◦ Bouyancy (water) ◦ Friction Some forces do not make contact and are non-contact forces. ◦ Gravitational forces ◦ Electrostatic forces ◦ Magnetic forces