Video Transcript
An object with a mass of 1.25
kilograms has a velocity of 12 metres per second. What is the object’s kinetic
energy?
So in this scenario, we have this
object. And we’re told that it has a mass,
we’ll call it 𝑚, of 1.25 kilograms. And also, it has a velocity that’s
nonzero. The velocity, which we’ll call 𝑣,
is 12 metres per second. We want to solve for the object’s
kinetic energy, that is, its energy due to motion. And to do that, we can recall the
mathematical relationship for kinetic energy. An object’s kinetic energy is equal
to one-half its mass times its velocity squared. So our object’s kinetic energy,
we’ll just call it KE, is equal to one-half its mass, 1.25 kilograms, multiplied by
its velocity, 12 metres per second squared. Notice that the units for mass and
velocity are in the base units of kilograms and metres per second. That means we’re all set to go. And we can multiply through on the
right side of this equation. When we do, we find the result of
90 kilograms metre squared per second squared or 90 joules. That’s how much kinetic energy this
object has.
