# Parachutist jumping from plane Conservation of Energy

1. Feb 26, 2009

### Jordash

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

A parachutist with mass m = 70 kg jumps from an airplane traveling at a speed v = 100 km/h at a height H = 2500 m and lands with a speed vf = 5.00 m/s. Use the “conservation of energy strategy” to calculate the change in internal energy of the system from just after the jump until just before landing. (1E6)

2. Relevant equations

PE+KE=PE[f]+KE[f]

3. The attempt at a solution

I'm thinking that where it talks about the airplane traveling at 100 km/h makes no difference in this problem. So the actual initial velocity would be vi=0km/h then I think I would calculate the velocity without Air Resistance and then factor in the difference of speed. Am I headed in the right direction.
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

2. Feb 26, 2009

### Delphi51

He will have speed 100 km/h initially. Don't forget to convert to m/s.

3. Feb 26, 2009

### Jordash

Why though? is the plane traveling downward?

4. Feb 26, 2009

### Delphi51

Direction is not important in calculating energy. The parachutist will have a horizontal speed of 100 - same as the plane - when he first lets go.