A thrown ball is in mid-flight: above the ground AND moving.
It holds kinetic energy because it moves, and gravitational potential energy because it is up there. Both at once.
The three stores this topic has built keep turning up together. What do we call their total?
Put numbers on the mid-flight ball: 9 J of kinetic energy from its motion, 21 J of gravitational potential energy from its height.
Together the ball carries 9 + 21 = 30, so 30 J sit in its motion and height combined.
A third store can join: a dart pressed against a compressed launcher spring holds elastic potential energy, even while nothing moves.
Which energies add up to an object's mechanical energy?
An object does not need all three. A wagon parked at the top of a hill holds only GPE; its mechanical energy is just that one store.
A kicked soccer ball is rising above the field. Name the mechanical energy stores it holds at that instant.
The ball moves, so it holds kinetic energy.
The ball is above the field, so it holds gravitational potential energy.
No spring or stretched material acts on it, so it holds no elastic potential energy.
The ball's mechanical energy sits in two stores: kinetic and gravitational potential.
A thrown baseball is above the field and moving. Which two mechanical energy stores does it hold at that instant?
One energy is deliberately left out. The thermal energy of warm brakes is real energy, but it is not kinetic or potential, so it is not part of mechanical energy.
At one instant, a cart holds 14 J of kinetic energy and 26 J of gravitational potential energy, with no elastic store. State its mechanical energy.
Mechanical energy is the stores' total: ME = KE + GPE + EPE.
Here the elastic store is 0 J, so the total is 14 + 26 = 40.
The cart's mechanical energy is 40 J.
Abril says: a clamped, compressed spring that is not moving still has mechanical energy. Is Abril right?
Later lessons track this total through a motion. That is why it gets its own name: the total is the thing worth watching.
Which of these objects holds mechanical energy in two stores at once?
At one instant a drone holds 45 J of kinetic energy and 80 J of gravitational potential energy, and no elastic store. Enter its mechanical energy in J.
A car drives down a mountain road. Which of these energies is NOT counted in the car's mechanical energy?