- #1

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w = FD

4. A force of 100 newtons was necessry to lift a rock. A total of 150 joules of work was done. How far was the rock lifted??

Please i really need to understand how to do this problem, if anyone reply's please try to give step by steps

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- Thread starter Jajo
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- #1

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w = FD

4. A force of 100 newtons was necessry to lift a rock. A total of 150 joules of work was done. How far was the rock lifted??

Please i really need to understand how to do this problem, if anyone reply's please try to give step by steps

- #2

cristo

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w = FD

4. A force of 100 newtons was necessry to lift a rock. A total of 150 joules of work was done. How far was the rock lifted??

Please i really need to understand how to do this problem,if anyone reply's please try to give step by steps

Well, I'm not going to do it for you! You have an equation with three variables. You know two of them, and want to find the third. How do you think you should do this?

- #3

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- #4

cristo

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You have the equation W=fd. Try rearranging this to make d the subject (i.e. to get d on its own). Can you do this?

[Hint: What does the equation look like if you divide both sides by f?]

- #5

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so i would divide d to both sides so it would be w/d = f right?

- #6

cristo

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No; you want to find d.so i would divide d to both sides so it would be w/d = f right?

Did you read this?

[Hint: What does the equation look like if you divide both sides by f?]

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so f = 1.5 meters or newtons or joules

- #8

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so f = 1.5 meters or newtons or joules

No. The number is correct, but which one of those units do you mean, they are not equivalent.

- #9

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- #10

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I made a mistake in my last post, you're correct in thinking it should be D, not f that is 1.5, but still it cannot be any one of those units they are not equivalent. So which is it newtons, meters or joules?

- #11

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F=100N, right?

W=150J, right?

If W=FD, and you have F and W, but want to know D, set rearrange the equation to isolate the D.. W/F=D.. 100N/150J=1.5 meters.

Why 1.5 METERS? Well, Newtons is a metric unit, and Joules is a metric unit.. And the metric unit for distance is meter. Or.. you could expand the newtons and joules..

Newton=kg*m/(s^2)

Joule=kg*(m^2)/(s^2)

Back to the problem.. [100*kg*m/(s^2)] / [150 kg*(m^2)/(s^2)]

That should result in 1.5, and all the units except meters cancel out, therefore, 1.5 meters.

- #12

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F=100N, right?

W=150J, right?

If W=FD, and you have F and W, but want to know D, set rearrange the equation to isolate the D.. W/F=D.. 100N/150J=1.5 meters.

Why 1.5 METERS? Well, Newtons is a metric unit, and Joules is a metric unit.. And the metric unit for distance is meter. Or.. you could expand the newtons and joules..

Newton=kg*m/(s^2)

Joule=kg*(m^2)/(s^2)

Back to the problem.. [100*kg*m/(s^2)] / [150 kg*(m^2)/(s^2)]

That should result in 1.5, and all the units except meters cancel out, therefore, 1.5 meters.

Please don't provide complete solutions to homework problems.

- #13

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- #14

cristo

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The OP had the correct numerical answer, however had not answered d_leet's question re the units. Besides, check out the PF guidelines: https://www.physicsforums.com/showthread.php?t=5374

guidelines said:Under no circumstances should complete solutions be provided to a questioner, whether or not an attempt has been made.

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