1. Friction and Gravity Review
(There are a total of 12 questions. As you view each slide, try to answer each question. The correct answer immediately follows each question)

2. #1
A force that tries to stop moving or prevent nonmoving objects from moving is called ______________.

3. #1
A force that tries to stop moving or prevent nonmoving objects from moving is called friction.

4. #2 Which shoes would create the least friction and why?
Nike running shoes
Tap shoes
Hiking boots
Vans sneakers

5. #2 Which shoes would create the least friction and why?
Nike running shoes
Tap shoes (smoothest bottom surface)
Hiking boots
Vans sneakers

6. #3 Which object would have the largest air resistance and why?
A watermelon
A pea
A surfboard
An iPod

7. #3 Which object would have the largest air resistance and why?
A watermelon
A pea
A surfboard (larger surface area)
An iPod

8. #4
Name the two types of friction represented in the picture below and where they are represented.

9. #4
Name two types of friction represented in the picture below and where they are represented.
Static friction - person’s feet and the chariot floor
fence and the sand
Sliding friction - horse hooves and sand
chariot/person/horses and air
wheels and sand

10. #5
An attractive force that pulls objects towards one another is known as ______________.

11. #5
An attractive force that pulls objects towards one another is known as gravity.

12. #6 Match each example with its correct type of friction
___i. Static Friction a. Trying to get a refrigerator to move
___ii. Sliding Friction b. Skateboard wheels turning over a sidewalk
c. Dragging a box across the floor
d. Ice skates gliding along the ice

13. #6 Match the type of friction with its correct example
A Static Friction a. Trying to get a refrigerator to move
B, C, D Sliding Friction b. Skateboard wheels turning over a sidewalk
c. Dragging a box across the floor
d. Ice skates gliding along the ice

14. #7 Which scenario would have the largest gravitational pull and why? AB C

15. #7 Which scenario would have the largest gravitational pull and why? AB
The objects are closer together C

16. #8
According to Newton’s 2nd Law, the platform diver will _____________ towards Earth because he has mass and ___________ is the net unbalanced force acting on him.

17. #8
According to Newton’s 2nd Law, the platform diver will accelerate towards Earth because he has a mass and gravity is the net unbalanced force acting on him.

18. #9
If three ice skaters are all wearing the same skates, which would create the least friction with the ice and why?
A 30-kg child
A 65-kg ice dancer
A 100-kg hockey player

19. #9
If three ice skaters are all wearing the same skates, which would create the least friction with the ice and why?
A 30-kg child (makes less contact with the ice)
A 65-kg ice dancer
A 100-kg hockey player

20. #10
Which free-falling object would have the greatest acceleration in a vacuum (outer space) ?
A watermelon
A pea
A surfboard
An iPod

21. #10
Which free-falling object would have the greatest acceleration in a vacuum?
A watermelon
A pea
A surfboard
An iPod
None. All would have the same acceleration without air resistance.

22. #11
• What is the acceleration due to gravity here on Earth is _____ m/s2 ?
• Explain what this number means.

23. #11
• What is the acceleration due to gravity here on Earth is 9.8 m/s2 ?
• Explain what this number means.
Every second, the object gains 9.8 m/s of speed.
Time Speed
0s = 0 m/s
1s = 9.8 m/s
2s = m/s
3 s = m/s

24. #12
Which planet would have a larger gravitational pull and why?

25. #12 Which planet would have a larger gravitational pull and why?
Jupiter - because it has significantly more mass