Motion and Forces

1. Motion and Forces

2. Question 1: • Answer: A

3. Agenda • Explain how force and velocity are related. • Describe what inertia is and how it is related to Newton’s first law of motion. • Identify the force and motion that are present during a crash.

4. What is force? • Force – is a push or pull that one body exerts on another. • Examples • Atmosphere • Weight

5. Changing motion • What happens to an object when a force is exerted on it? • The object at rest moves in the direction of the force.

6. Balanced force?

7. Balanced force • Balanced force – forces on an object that are equal in size and opposite in direction. • Net force – when two or more forces act on an object at the same time. • Net force = zero

8. Unbalanced forces - Unequal forces in opposite directions, a net force occurs in the direction of the greater force.

9. What do these images have in common?

10. Inertia and Mass • Inertia – is the tendency of an object to resist any change in motion. • The velocity of an object remains constant unless an unbalanced force acts on it.

11. Could an astronaut move the space station by himself? No, though it is "weightless" it still has mass!

12. Why would it be very difficult to catch a bowling ball like you would a tennis ball? • A greater force would be needed to change the motion of the bowling ball because it has greater inertia. • Inertia is related to the mass of an object • Greater the mass, greater the inertia.

13. Newton’s first law of Motion • Sir Isaac Newton – stated the rules that describe the effects of force on the motion of objects. • First law of Motion or Law of Inertia– an object moving at a constant velocity keeps moving at that velocity unless a net force acts on it. • Object at rest, stays at rest unless a net force acts on it.

14. Balanced or unbalanced?