IGCSE Physics

1. Forces and Their Effects Physics Checkpoint @ferrytanoto

2. You cannot see a force but you can see what it does. You can also feel the effect of a force on your body.

3. A force is a pushor a pull

4. What can a force do?

5. A force can make an object move.

6. A force can make a moving object stop.

7. A force can change the speed of a moving object. A force can accelerate an object. The larger the force on the object, the greater the acceleration if the mass stays constant. The larger the mass of the object, the smaller the acceleration if the force stays constant. Newton’s Second Law of Motion: Force (N) = mass (kg) x acceleration (m/s2)

8. A force can change the direction of a moving object.

9. A force can change the shapeof an object.

10. How to measure a force?

11. A force can be measured with a Newton spring balance.The SI unit for measuring force is the Newton (symbol N).

12. There are two main types of forces: contact forces and non-contact forces.

13. A contact force occurs when the object or material exerting the force touches the object or material on which the force acts.

14. A non-contact force occurs when the objects or materials do not touch each other.

15. Contact Forces Impact force When a moving object collides with a stationary object an impact force is exerted by one object on the other. Strain force When some materials are squashed, stretched, twisted or bent they exert a force which act in the opposite direction to the force acting on them. These materials are called elastic materials and the force they exert when they are deformed is called a strain force.

16. Impact force When a moving object collideswith a stationary object an impact force is exerted by one object on the other.

17. Strain force When some materials are squashed, stretched, twisted or bent they exert a force which act in the opposite direction to the force acting on them. These materials are called elastic materials and the force they exert when they are deformed is called a strain force. When the force applied to the material is removed the strain force exerted by the material restore the deformed material to its original shape.

18. Tension Tension is a strain force that is exerted by a stretched spring, rope or string. At each end the tension force acts in the opposite direction to the pulling force.

19. Non-contact ForcesThey all exert their force without having to touch the object Magnetic forces Electrostatic forces Gravitational forces

20. Magnetic Force A magnet has a north-seeking pole and a south-seeking pole, known as north pole and south pole. If you pick up two magnets and bring them together, you will feel a force either pushing or pulling each other. The same poles attract each other while different poles repel each other.

21. Magnetic Force A magnet can also exert a non-contact force on objects made ofiron, steel, cobalt or nickel. Either pole of the magnet exerts a pulling force on these magnetic materials. The strength of the force increases as the magnet and the magnetic material are brought closer together.

22. Maglev (Magnetic Levitation) Train

23. Maglev (Magnetic Levitation) Train

24. Electrostatic Force If certain electrical insulator materials are rubbed an electrostatic charges (positive charge and negative charge) develop on them. Similar charges repel each other while opposite charges attract each other.

26. G is the gravitational constant (which is approximately equal to 6.674×10−11 N m2 kg−2)

27. m1 is the first mass,

28. m2 is the second mass, and

29. r is the distance between the masses.The force that exists between any two masses because of their mass is called the gravitational force.

30. Gravitational Force The gravitational force between the Sun and all the planets in the Solar System holds the planets in their orbits The gravitational force between an object on the Earth and the Earth itself pulls the object down towards the centre of the Earth and is called the weightof the object.

31. Robert Hooke The extension of a spring is proportional to the mass attached to it. F = kx F = applied force (N), x = extension (m), k = force constant for object under test (N/m) However, the addition of mass to a spring beyond a limit, called the elastic limit, it no longer extends proportionally to the mass anymore. It is permanently deformed. The spring beyond its elastic limit was in a state known as plastic deformation.

32. A Spring Balance This instrument uses Robert Hooke’s discovery. The scale on the balance is calibrated in newtonso it is sometimes called a Newton Spring Balance or a newtonmeter. 5 N 5 N