# Homework Help: Just some questions

1. Mar 22, 2005

### mark9159

1) in what way could angular momentum be changed?
Ans) alter the mass, alter the angular velocity, and redistribute the mass

2) You have one screwdriver with a thick handle and one with a thin handle. Which one would be better for opening a stubborn can of paint?
Ans) Either screwdriver--they are the same. I picked this answer because the i believe that the thickness of the handle does not interfere with the screwdriver's ability to pry open a can of paint

3) Which screwdriver would be better for turning a stubborn screw?
Ans) The thick-handled screwdriver

4) How do we know that a force from the earth acts on the moon?
Ans) I put because the moon orbits the earth

5) What force keeps the moon in orbit around the earth?
Ans) Gravitational force

6) You turn a corner in your car and slide to the outside edge of the seat. Why does this happen?
Ans) Centrifugal force pulls you to the outside

What kind of force does friction provide when your car turns a corner?
Ans) centripetal

8) On a carnival ride, what force keeps you moving in a circle with the ride?
Ans) Centripetal

And can someone explain to me what i should do to solve this problems..with hints, and not answers preferbably.

What linear distance corresponds to a drop in the earth's surface of 4.9 meters?

thank you very much

2. Mar 22, 2005

### HallsofIvy

1. redistributing mass does not change the angular momentum.

"What linear distance corresponds to a drop in the earth's surface of 4.9 meters?"

?? 4.9 meters is a "linear distance"! I don't know what else that could mean.

3. Mar 22, 2005

### mark9159

"In what way could angular momentum be changed?"

a) alter the mass

b)alter the angular velocity

c) redistribute the mass

d) all of the above

i picked all of the above because altering the mass and altering the velocity both change angular momentum..can you please explain this to me?

4. Mar 22, 2005

### HallsofIvy

Could you explain your answer to me?? You say "i picked all of the above because altering the mass and altering the velocity both change angular momentum". How is the fact that you knew a and b were correct a reason for saying "all of the above" and including c?

Take the typical example of a skater doing a spin. She moves her arms inward, not changing her mass but "redistributing" her mass. What happens to her angular velocity? Why? (What happens to her angular momentum?)

5. Mar 22, 2005

### DaveC426913

2) You have one screwdriver with a thick handle and one with a thin handle. Which one would be better for opening a stubborn can of paint?

Your answer is generally correct, but it depends on how picky you want to get. A thick-handled screwdriver will distribute the force over the palm of your hand better, meaning you can apply more force before getting hurt.

6) You turn a corner in your car and slide to the outside edge of the seat. Why does this happen?
Ans) Centrifugal force pulls you to the outside

No. Centrifugal force is an illusion. Hint: there is a "property" you have that causes you to continue in the same direction while the car turns.

What linear distance corresponds to a drop in the earth's surface of 4.9 meters?

Uh ... that would be ... 4.9 meters?