Another Physics question.....?

Question

Spring scale A is attached to the floor and a rope runs vertically upward, loops over the pullley, and runs down on the other side to a 120-N weight. Scale B hangs a 120-N weight. What are the readings of the two scales A and B? The weights of the scales are negligible.

Any help is appreciated...Thanks

Answer 1

Scale B = 120g
Scale A = 60g

g is the gravity = 9.81 ms-2

Hope this help... Try to do a vector analysis to reslove this problem as i cannot upload the picture here.....

Answer 2

Does 120-N mean 120 Newton? If so, g doesn't come into it unless we want to work back to mass.

Obviously scale B reads 120 Newton

In fact both weights require an upward force of 120 N to be applied to hold them up. So even for scale A, the tension in the rope must be 120 N and therefore that's the reading on scale A.

Answer 3

According to Newton's third law, scales A& B must have the same reading of 120 N.
Iimagine scale A attached to the ceiling, remove the pulley you will have clear idea.

Answer 4

Trick question, but straightforward. As a simple pulley provides no mechanical advantage, the force applied by the weight to Scale A is the same as that applied to Scale B.

Both scales will read 120.

Answer 5

-120, +120

Answer 6

Try to solve it with help of vectors

Try these sites may be you find something useful
www.physics.harvard.edu/academics/undergrad/problems.html
www.physicsclassroom.com/Class/vectors/u3l1b.html
www.physics.uoguelph.ca
www.physics.ucsb.edu/~phys21/w2005/problems/p10.pdf
www.physicsclassroom.com/Class/vectors/U3L2e.html