# Velocity from a force time graph

## Homework Statement

The figure is a graph of the force exerted by the floor on a woman making a vertical jump.
At what speed does she leave the ground? Hint: The force of the floor is not the only force acting on the woman.

## The Attempt at a Solution

I am completely lost with this question. First I derived her mass from the 600N from the graph. Which was about 61.22kg

Then I calculated the Impusle from the area underthe graph, but where from? All the area or minus the forces of gravity? then I used:

Impulse= m(delta v)

But Im not getting anywhere :(

#### Attachments

• image022.jpg.jpeg
4 KB · Views: 1,279

Astronuc
Staff Emeritus
Starting with this: Impulse= m(delta v)

Then delta v = Impulse/m, and delta v = v - vo, and vo = ?

Im guessing Vo is zero becasue she is jumping straight up?

Do I calculate Impulse to be the entire area under the graph or just a certain segment under the graph?

Astronuc
Staff Emeritus
Im guessing Vo is zero becasue she is jumping straight up?
Correct. Standing she starts are rest.

Do I calculate Impulse to be the entire area under the graph or just a certain segment under the graph?
Weight which is a force, does not provide for acceleration. One has to consider the force in excess of the weight.

Correct. Standing she starts are rest.

Weight which is a force, does not provide for acceleration. One has to consider the force in excess of the weight.

So since F=mg, and I derived mass from 600/9.8. does that mean that the impusle is the area of the graph from anything that is >600n?

Astronuc
Staff Emeritus