Physics question?

Question

In bench pressing 1.0 x 10^2 kg, a weight lifter applies a force of 1040 N. How large is the upward acceleration of the weights during the lift?

Answer 1

Well, I don't know how your physics teacher taught you to do it, but my teacher taught us to do it with summations.

The summation (adding all of them up, that is) of all of the forces in the x (horizontal) direction is 0, because there are no forces in that direction.

The forces in the y (vertical) direction will all add up to the mass of the weights times their acceleration (based on Newton's Second Law of Motion).

Let's just say...
Fy = ma

Fy = Fapplied - Fweight = ma
Fy = 1040 N - (100 kg)(9.8 m/sec^2) = (100 kg)(a)
Note: 9.8 m/sec^2 is the acceleration of gravity
Multipy to find the weight and isolate the acceleration variable.

a = (1040 N - 980 N) / (100kg)
a = (60 N) / (100 kg)
a = 0.60 m/sec^2

And there you have your answer.

Also, as you can see, no time was needed ;)

Answer 2

Your question needs some kind of time conponent.