A model rocket weighing 30 grams lands with a speed of 30m/s. What is its kinetic energy on impact?
1/2 X 0.03 X 30 X 30 = 13.5 joules
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A model rocket weighing 400 grams is launched to a height of 100m. All its gravitational energy is converted into kinetic energy on impact.
What is its kinetic energy on impact?
Since energy can not be created or destroyed the gravitational potential energy is converted into kinetic on impact.
mgh = 0.4 X 9.8 X 100 = 392 joules = kinetic energy
=> V = 44.27 m/s
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Kinetic energy

Kinetic energy is the energy due to movement. Any object that moves has kinetic energy. The faster an object moves the more kinetic energy it possess. Kinetic energy has the formula 
where m is the mass of the object and v is its velocity. Example 1. A toy car weighing 20 grams moves at a speed of 6 metres per second. Its kinetic energy is ½ X 20 X 6 X 6 = 360 Joules of energy.
Example 2. A
rocket weighing 100 Kilograms hit the ground at a speed of 300m/s. What
is its kinetic energy on impact? 1/2 X 100 X 300 X 300 = 4,500 kilojoules Always convert the mass into kilograms.
1) A model rocket weighing
30 grams lands with a speed of 30m/s. What is its kinetic energy on impact?
2) A model rocket weighing 400 grams is launched to a height of 100m. All its gravitational energy is converted into kinetic energy on impact. What is its kinetic energy
on impact? 3) A 500kg
spacecraft hurtles towards Earth at a speed of 200m/s. Calculate the kinetic
energy of the craft. 4) A 2,300gram
explosive shell is launched at a speed of 300 kilometres/minute. Find
its kinetic energy at launch. 