# Homework Help: Need Help NOW

1. Dec 19, 2013

### tdotot

What is the minimum force needed to overcome static friction on a block whose normal force is 5.2N and has a coefficient of static friction 0.34?

A desk is pushed with a constant velocity along a floor. If the mass of the desk is 25kg,and the force required to keep the desk moving is 45N,determine the coefficient of friction between the desk and the floor.

A 688 kg car is driving to the right at a constant velocity. The engine exerts a force of 855N. Find the coefficient of friction.

What is gravational force extended on the Earth by the Sun? (Mass of sun=1.989x10^30kg,distance from earth to the sun=149,600,000km,mass of Earth=5.98x10^24)

If your weight on the surface of a planet is 350N and you decided to drill half way to the center of the planet,what would your new weight be at your new depth underground?

Orbiting Planet X at distance R from the center of the planet, someone has a weight of 400N. What would his weight be if he was 3 times as far away from the center of Planet X and this planet was three times as massive?

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Can anyone answer any of these 6? Even 1 is useful, thanks, please show full steps

2. Dec 19, 2013

### tdotot

Anyone please? I have an exam tomorrow :/

3. Dec 19, 2013

### SteamKing

Staff Emeritus
Sorry. You must show some work in order to receive help. Those are the rules for the HW forums. We don't do your HW for you, we don't study for you, and we obviously can't take your tests.

PS: It's also recommended that only one HW problem be given per thread. This cuts down on long and confusing replies to your post.

4. Dec 19, 2013

### tdotot

I have no clue which formula to use. If you can give me a formula then I can try to attempt some work.

5. Dec 19, 2013

### Panphobia

You should be trying to understand concepts and not attaining formulas. This is because when you are writing your exam and something more difficult than what you have memorized pops up you won't be able to handle it. Did you even go/(pay attention) in class? If your exam is tomorrow, your teacher should have brought up how to solve these types of questions earlier in the semester.

6. Dec 19, 2013

### Staff: Mentor

https://www.physicsforums.com/blog.php?b=4714 [Broken]

Last edited by a moderator: May 6, 2017