1. QOD#48 D What does each line represent? A – B – C – D – B C A Distance
Acceleration (speeding up)
Stopped – no motion C A
Constant Speed
deceleration (slowing down)
Time

2. Forces
Force – a push or pull on an object. Unit – Newtons (N)

3. Types of Forces Contact forces
________________ - a force that is applied when two objects touch.
1. Push
ex:
2. Pull

4. Friction Air resistance Buoyancy
3. ___________________ - the resistance between two surfaces that are in contact with each other (sliding against each other). ex: 4. ___________________ - the force exerted on an object by the air as its moving. (drag force) 5. ___________________ - the upward force exerted by a fluid, which opposes the weight of an object.
Air resistance
Buoyancy

5. Non-Contact Force Magnetic Force Electric Force Gravitational Force
B. ____________________ - a force that one object applies to another object without touching. 1. ____________________ ex: 2. ____________________ (includes static electricity) 3. ____________________
Magnetic Force
Electric Force
Gravitational Force

6. Gravity
Lift
Thrust (push)
Drag (air resistance)
Gravity
Buoyancy

7. Forces WS

8. Measuring Force
Force is measured in Newtons (N) 1 Newton = lifting a stick of butter 20 Newtons = lifting a 2-L bottle of soda

9. Measuring Force Activity
Object
Weight in Newtons (N)

10. QOD #49 Falling Feather & Golf Ball
1. What happens when we drop a golf ball and a feather down a stairwell? 2. Why does this happen?

11. Gravity
Weight
________________ – the gravitational force exerted on an object. Every object (that has mass) exerts a __________________________ of attraction on any other object.
gravitational force

12. Mass The greater the mass of two objects, the ________________ the gravitational force is between them.
greater
Does the earth & the person or the moon & the person have a greater gravitational force between them? Why?

13. Which person will feel a greater force of gravity with the earth?
Distance
The force of gravity increases as two objects become ____________ (as the distance between the objects ______________).
The force of gravity decreases as two objects ____________________ (as the distance between the objects ______________).
closer
decreases
move farther apart
increases
Which person will feel a greater force of gravity with the earth?

14. 1. Between which two objects is there the greatest gravitational force (based on their mass)? a. b. c. 2. Between which two objects is there the greatest gravitational force (based on their distance)?

15. What is the speed of a giraffe if it travels 400 meters in 40 seconds?
QOD#50
What is the speed of a giraffe if it travels 400 meters in 40 seconds?

16. Balanced/Unbalanced Forces
Forces are described in terms of ___________ and ____________ (strength).
direction
magnitude
Ex1: Pushing the box to the right
100 N
Ex2: Downward gravitational force
3 N

17. net force
The ______________ is the combination of all the forces acting on an object.
Gravitational force of 15 N
Ex3:
Lift force of 15 N
Net force: __________
0 N
Ex4:
1,050 N
Net force: __________
650 N
400 N

18. Ex5:
125 N
375 N
250 N
Net force: __________

19. Balanced forces stays still Ex6: 0 N
____________________ – forces acting on any object that combine and form a net force of zero. -When balanced forces are acting on an object, the object _________________.
Balanced forces
stays still
Ex6:
300 N
300 N
Net force:
__________
0 N

20. Unbalanced forces motion Ex7: 100 N
__________________ - forces acting on an object that combine to a net force that is not zero. -Objects go into ___________ because of unbalanced forces.
Unbalanced forces
motion
Ex7:
400 N
500 N
Net force:
__________
100 N

21. Balanced/Unbalanced WS