Classical Mechanics

Kinetic Energy

Kinetic energy of an object


A 14 kg14\text{ kg} object initially at rest starts to fall freely. If air resistance is negligible, what is the object's kinetic energy after 0.50.5 seconds?

The gravitational acceleration is g=10 m/s2.g=10\text{ m/s}^2.

What is the kinetic energy of a 6 kg6\text{ kg} object moving at 10 m/s?10\text{ m/s}?

A car of mass 1900 kg1900\text{ kg} is traveling at 28 m/s28\text{ m/s} on a street that has a speed limit of 20 m/s.20\text{ m/s}. The driver spots a police car and reduces its speed to match the speed limit. How much kinetic energy did the car lose?

A 10 kg10\text{ kg} object, AA, travels at 6 m/s,6\text{ m/s}, and a 6 kg6\text{ kg} object, BB, travels at 10 m/s.10\text{ m/s}.

Find the ratio K.E.A/K.E.B\text{K.E.}_A/\text{K.E.}_B.

Recently, a meteor impacted Russia. The estimate of the meteor's size was 10 tons10~\mbox{tons} and it was estimated to have entered the earth's atmosphere at a speed of 14,600 m/s14,600~\mbox{m/s}. What was the total kinetic energy of such a meteor J\si{\joule} as it entered the atmosphere?

Details and assumptions

  • One ton is 907 kg907~\mbox{kg}.

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