Physics/Mathematics help Plz!!! Someone help me understand it?

Question

OK so I have these questions but I also want to know how to do them. My teacher couldn't explain to me how to get the answers to these questions. Please help!

1. Work = 20N X 100m

2. 60J = 30N X distance?

3. 20J = force? X 2m

4. Work? = 10N X 500m

5. Work? = .2N X 600m

6. 5,000J = 500N X distance?

7. Work? = 82N X 76m

8. Work? = 820N X 205m

9. Work? = 20N X 0m

10. 200 W = 2000 J / Time?

11. 15 W = Work? / 10 sec

12. Power? = 56 J / 2 sec

13. Power? = 324 J / 18 sec

14. Power? = 500 J / 50 sec

15. Power? = 2,400 J / 60 sec

Thanks

Answer 1

Work (units of Joules) is the product of Force (in Newtons) and distance (in meters). So your first problem is

Work = 20 N x 100 m = 2000 J

Power (the unit is Watt) is Work (in Joules) divided by time (in seconds). So your last problem is

Power = 2,400 J / 60 s = 40 W

The first nine problems all use the first equation; the remaining problems use the second one.

Answer 2

Most of these questions are simply trying to get you to multiply two numbers together to get the answer - probably to get you used to work energy equations. While you are dividing the numbers, you are also dividing the units as well. Power = energy / time - so q 14 is saying power is joules per second, or watts as well as saying 10 J/s.

anyway q1.

Work done = force X distance

Force is measured in Newtons and distance in metres. So the answer to question 1 is 20N X 200m = 4000 Nm, or 4000Joules.

For some of the other equations, then you have to rearrange the equation to get the answer you need - like question 2. Divide both sides by 30N...

60J/30N = 30N/30N X distance
2J/N=1X distance
2m = distance.

I suspect your teacher is trying to make you have a stab at doing the question. If you are still having a problem, why not ask him/her again. If they genuinely can't help you, then find a maths teacher who can. You deserve better!

Take care