Impulse and momentum question, relates to Biomechanics

1. May 11, 2013

urbano

1. The problem statement, all variables and given/known data

A male and female pair of dancers start dancing when the male lifts the female and throws her into the air. The female's mass is 40kg . The male exerts an average vertical force of 500n for 1.0s on the female.

What is her vertical velocity when she is released into the air ?

2. Relevant equations

I chose to go with Force x Change in time = Mass x Change in Velocity
FΔt = mΔv

3. The attempt at a solution

So I initially came up with

500N x 1.0s = 40kg x Change in velocity

(500N x 1.0s)/ 40kg = Change in Velocity

Change in velocity = 12.5

The correct answer (if 9.81 m/s is used for g) is 2.69 m/s upwards. I hadn't accounted for g in my answer and am not sure how to incorporate it.

2. May 11, 2013

Staff: Mentor

Is the force that the man exerts on her the only force acting on her?

3. May 11, 2013

urbano

to the best of my knowledge yes, I have literally written out the question as it was presented.

4. May 11, 2013

Staff: Mentor

Don't forget gravity. (That's where g comes in.)

5. May 11, 2013

urbano

yes this is where I'm confused...how do you incorporate g into it ?

6. May 11, 2013

Staff: Mentor

There are two forces acting on the woman: The upward push from the man and the downward pull of gravity (her weight). You need to use the net force to calculate her change in velocity.