if a 1 kg rock is thrown at a speed of 20m/s, how much kinetic energy does it have?
To calculate the kinetic energy of an object, you can use the formula: KE = 1/2 * m * v^2, where KE is the kinetic energy, m is the mass, and v is the velocity or speed of the object.
In this case, you have a 1 kg rock that is thrown at a speed of 20 m/s. Plugging these values into the formula, you can calculate the kinetic energy as follows:
KE = 1/2 * m * v^2
= 1/2 * 1 kg * (20 m/s)^2
= 1/2 * 1 kg * 400 m^2/s^2
= 200 J (joules)
So, the 1 kg rock thrown at 20 m/s has a kinetic energy of 200 joules.