A 20 kg object falls from a height of 30 meters. The amount of kinetic energy that the object will have just before it hits the ground is ______ joules.
Assuming no air resistance, the kinetic energy gained equals the potential energy lost, namely
PE=KE=mgh
m=20 kg
g=9.8 m/s²
h=30 m
therefore
KE=mgh=?
To find the amount of kinetic energy that the object will have just before it hits the ground, we can use the formula for kinetic energy:
Kinetic Energy (KE) = 1/2 * mass * velocity^2
First, we need to find the velocity of the object just before it hits the ground. We can use the equation for gravitational potential energy to find the object's velocity:
Gravitational Potential Energy (PE) = mass * gravity * height
where mass is the mass of the object, gravity is the acceleration due to gravity (9.8 m/s^2), and height is the height from which the object falls.
Plugging in the given values, we have:
PE = 20 kg * 9.8 m/s^2 * 30 m
= 5880 joules
Next, we can equate the gravitational potential energy to the kinetic energy since the object will lose potential energy while gaining kinetic energy as it falls:
PE = KE
5880 joules = KE
Therefore, the amount of kinetic energy that the object will have just before it hits the ground is 5880 joules.