Crumple zones built into modern cars also serve the purpose of reducing force by increasing the collision time. Crumple zones cause cars to be totaled more often, but cars can be replaced and people can’t be. Notice that the presenter in the previous video isn’t talking about or , but he does keep mentioning absorbing . This energy that he is claiming will be absorbed by the crumple zone is the energy stored in the motion of the car. Any moving object has this type of energy, known as (KE). The amount of kinetic energy an object has depends on its and its :
Notice that the depends on , but not because KE doesn’t have a direction (an object can’t have negative KE). Even if we input a negative velocity into the KE equation, it gets squared so KE would come out positive anyway. The unit of kinetic energy is a Nm, which has it own name, the (J).
What is the of a person with 65 kg running with a of 10 m/s?
What is the of a meteorite with 100x less mass than the person above, but entering the atmosphere at 100x greater speed (0.65 kg and 1000 m/s)?
Which is larger, the KE of the runner or the meteorite?
What matters more in determining , or ?
the average force applied during a time interval multiplied by the time interval
the combined effect of mass and velocity, defined as mass multiplied by velocity
A quantity representing the capacity of an object or system to do work.
energy which a body possesses by virtue of being in motion, energy stored by an object in motion
a measurement of the amount of matter in an object made by determining its resistance to changes in motion (inertial mass) or the force of gravity applied to it by another known mass from a known distance (gravitational mass). The gravitational mass and an inertial mass appear equal.
distance traveled per unit time
a quantity of speed with a defined direction, the change in speed per unit time, the slope of the position vs. time graph
a system of physical units ( SI units ) based on the meter, kilogram, second, ampere, kelvin, candela, and mole
International standard (SI) unit of Energy