Answer:
Kinetic energy of boy just before hitting the ground is 1000 J.
Speed of boy just before hitting the ground is 7.67 m/s
or 17.16 mi/hr.
Explanation:
Given that:
Mass of boy = 75lb = 34 kg
Height, h = 10ft = 3m
To find:
Kinetic energy of boy when he hits the ground.
<em>As per law of conservation of energy The potential energy gets converted to kinetic energy.</em>
<em></em>
<em></em><em> </em>Kinetic energy at the time boy hits the ground = Initial potential energy of the boy when he was at the Height 'h'
The formula for potential energy is given as:
Where m is the mass
g is the acceleration due to gravity, g = 9.8
h is the height of object
Putting all the values:
PE =
Hence, Kinetic energy is 1000 J.
Formula for Kinetic energy is:
where m is the mass and
v is the speed
Putting the values and finding v:
Given that:
1 m = 1.094 yd and 1 mi = 1760 yd
Converting 7.67 m/s to miles/hour: