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

Answer:

Kinetic energy  = 135 kJ

Potential energy = 73.5 kJ

Explanation:

 Mass of sky diver = 75 kg

  Velocity = 60 m/s

   Height = 100 m

 Kinetic energy is given by the expression, $KE = \frac{1}{2} mv^2$, where m is the mass and v is the velocity.

  So Kinetic energy  = $\frac{1}{2} *75*60^2=135000J=135kJ$

 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

Answer 2

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

$P.E =75kg \times 10m {s}^{ - 2} \times 100m$
P.E =75000 J

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


Kinetic energy,K.E
$= \frac{1}{2}m {v}^{2}$

$= \frac{1}{2} \times 75 kg\times ( {60})^{2} m {s}^{ - 1}$

=135000 J

Hence the kinetic energy of the Skydiver is 135000 J