Mechanical Energy

If a person is standing still atop a hill, what is the formula for the person's mechanical energy?

• Ep = Ek

• Em = Ep

• Em = Ek

• Ek = Em + Ep

What is the formula for mechanical energy?

• Ep = Ek + Em

• Em = gv + (1/2)hm²

• Em = Ek + Ek

• Em = (1/2)mv² + mgh

When is kinetic energy at zero?

• A ball speeds downhill at 12m/s

• A ball gradually goes uphill at 3m/s

• A ball comes to a complete stop at the bottom of the hill

• A ball leaves the track flying upward at 2 m/s

If 50N of force is used to push a bow string back 0.1m how much potential energy is stored in the string?

• 500J

• 5J

• 50J

• 2J

At the top of a hill a 20kg boulder has 1440J of potential energy what is the maximum speed it reaches at the bottom of the hill?

• 12m/s

• 10m/s

• 13m/s

• 6m/s

If the work done lifting an 60kg anvil to the top of a tower is 3600J, after being dropped, what is the kinetic energy of the anvil as it hits the ground?

• 60J

• 600J

• 3.6J

• 3600J

What is the first law of thermodynamics?

• Energy is not created or destroyed, it is conserved.

• Not every conversion is 100%

• Mechanical energy is always potential + kinetic energy

• Lots of sugar = Lots of energy

What has more kinetic energy, a 10kg ball moving at 13m/s or a 20kg box moving at 7m/s?

• the 10kg ball

• the 20kg ball

• the 10kg box

• the 20kg box

The work done by a person walking up to the top of a 75m cliff is 55500J, what is the person's mass?

• 50kg

• 65kg

• 75kg

• 80kg

What is mechanical energy?

• gravitational stored energy + chemical stored energy

• stored energy + the energy of motion

• the energy of motion

• energy stored by position or status