Physical science help? Check my answers?

Need some help please D: 1. If you perform 10 joules of work lifting a 10 -N box from the floor to a shelf, how high is the shelf? (1 point)

A. 1 M

B. 2 m

C. 10 m (My answer )

D. 100 m

2. How can a machine make work easier for you? (1 point)

A. By decreasing the amount of work you do (My answer)

B. By changing the direction of your force

C. By increasing the work done by the machine

D. None of the above

3. How can you make the work output greater than the work input? (1 point)

A.By deceasing the friction

B. By increasing the input force ( My answer)

C.By increasing the output distance.

D. None of the above

4. Reducing the friction in a machine (1 point)

A. Decreases it's actual mechanical advantage ( My answer)

B. Decreases the work output

C.Increases it's efficiency

D. Increases it's ideal mechanical advantage

5. The ideal mechanical advantage of a pulley system is equal to the (1 point)

A. Distance the load has to move

B. Length of the rope

C.Number of rope segments supporting the load ( My answer)

D. Weight of the object being lifted

1 Answer

  • A Joule is equal to a Newton-meter, so if you expended 10 Joules of energy to lift a 10 Newton load then the distance is:

    D = 10 J (N-m)/ 10 N = 1 meter

    So #1 is A

    #2 is A

    #3 is impossible so the answer is D

    #4 is C. By reducing friction you reduce the losses and improve efficiency.

    #5 is C

    Hope this helps,


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