1. Without the force of gravity, what would the moon’s path be?
velocity Fg
Earth m Fg
Hint: Use Newton’s 1st law of motion

2. Newton’s second law of motion
The acceleration of an object is directly proportional to the net force applied to the object and inversely proportional to the object’s mass.

3. Use Newton’s second law to solve for acceleration.
If the object’s mass is 3 kg and a net force of 12 N is applied, what is the acceleration?

4. Use Newton’s second law to solve for acceleration.
If the object’s mass is 4 kg and a net force of 2 N is applied, what is the acceleration?

5. The acceleration due to gravity at the earth’s surface.
Notice that g represents a special acceleration. It does not stand for gravity.

6. The force of gravity between a person and the earth.
The person’s weight
= mpg
d is the radius of the earth
mE is the mass ot the earth
 is a constant
mp is the mass of the person
, mE, and d are the same for all objects at the earth’s surface.

7. Therefore g is inversely proportional to d2
= 10 m/s2 at the earth’s surface

8. What is the value of g, when an object is 4 times its original distance to the center of the earth?

9. Gravity is fundamentally a weak force

10. Weight is the force of gravity between an object and a planet.
The person’s weight
= mpg
If you double the mass of the planet, your weight will double.

11. The acceleration due to gravity on the moon:
gmoon= 2 m/s2

12. Moon walk
We would walk in slow motion on the moon because g on the moon is only 1/6 that on the earth’s surface.

13. When the string is cut, which path will the heavy ball take?
razor C B A

14. Conservation of angular momentum 
When the moment of inertia  decreases, the angular velocity must increase in order to conserve angular momentum.

15. This is a Newton’s 3rd law example
Force of gravity on the ball
from the earth.
What is the reaction force?
Earth

16. Newton’s second law reveals that the acceleration due to gravity is a constant, when air friction is ignored.
g is a special acceleration which equals 10 m/s2 near the earth’s surface.

17. Which vehicle will experience the greater force during collision?
Momentum transfer
Corp. V V
Hint: Use Newton’s 3rd law of motion.

18. Why is it safer to be in the truck?
Momentum transfer
Corp. V V
Hint: Use Newton’s second law of motion.

19. Acceleration is inversely proportional to the object’s mass.
The larger mass truck experiences a much smaller acceleration than the car. Acceleration kills.

20. What is the acceleration of the rock at the moment it reaches the top of its trajectory?

21. All objects, in free-fall, near the earth’s surface, accelerate down-disregarding friction of course.
Do you know the rate of acceleration?

22. Where should the zoo keeper aim if he knows that the monkey is not going to let go?

23. On which side is the acceleration greater?
kg
kg
100 N
100 N
10 kg
100 N
100 N
Hint: The total mass of both sides is not equal.

24. Is torque increased by the rope?

25. What does the spring scale read?
100 Newtons
100 Newtons
Zero, 100 N or 200 N?

26. Which path will the pellet take? Neglect gravity and air friction.B A C
Hint: Use Newton’s 1st law of motion.