Question

Suppose a skydiver (mass = 75kg) is falling toward the Earth. When the skydiver is 100m above the earth he is moving 60m/s. At this point calculate the skydivers.......

Gravational potential energy


Kinetic energy

Answer 1

From the question,
The mass of the skydiver,


`m=75kg`


The height from the Earth at which the skydiver is before falling,


`h=100m`


Velocity, V of the skydiver


`=60m {s}^( - 1)`



Let us take acceleration due to gravity to be ;

`g = 10m {s}^( - 2)`


The mass of the skydiver, m=75kg

The height from the Earth at which the skydiver is before falling, h=100m

Velocity, V of the skydiver =60m/s


Potential energy, P.E can be calculated from the relation;
P.E = mgh


`P.E =75kg * 10m {s}^( - 2) * 100m`
P.E =75000 J

Therefore, the gravitational potential energy of the skydiver is 75000 J


Kinetic energy,K.E

`= (1)/(2)m {v}^(2)`


`= (1)/(2) * 75 kg* ( {60})^(2) m {s}^( - 1)`

=135000 J

Hence the kinetic energy of the Skydiver is 135000 J

Answer 2

Kinetic energy = 135 kJ

Potential energy = 73.5 kJ

Step-by-step explanation:

Mass of sky diver = 75 kg

Velocity = 60 m/s

Height = 100 m

Kinetic energy is given by the expression,
`KE = (1)/(2) mv^2`, where m is the mass and v is the velocity.

So Kinetic energy =
`(1)/(2) *75*60^2=135000J=135kJ`

Potential energy is given by the expression, PE =mgh, m is the mass, g is the acceleration due to gravity value and h is the height.

So, Potential energy = 75*9.8*100 = 73500J = 73.5 kJ