What are the two forces involved when a machine is used?

-friction and density

-potential and kinetic

-input and output

-gravity and friction

What can cause a big city to be warmer than the surrounding countryside?

How do a neutron and a proton compare? A. There are more protons than neutrons in an isotope. B. They have about the same mass. C. The proton has a positive charge, while the neutron has a negative charge. D. The neutron is farther from the nucleus.

What is the formula for potential energy?

What determines all the star's properties such as its temperature, size, brightness and life span? a. Weight b. Mass c. Diameter d. Luminosity

a bowling ball is rolling down the hall at a constant speed of 1.5 m/s. how far will the ball roll in 6.0 s.

Which process causes wells on land to become saline, making them unusable for drinking water? A. Erosion B. Echo sounding C. Eutrophication D. Groundwater infiltration

A farmer uses a tractor to pull a 150 kg bale of hay up a 15∘ incline to the barn at a steady 5.0 km/h. The coefficient of kinetic friction between the bale and the ramp is 0.40. Part A What is the tractor's power output?

Identify the conditions for an elastic collision in a closed system. Check all that apply. Energy is conserved. Velocities may change. Momentum is conserved. Kinetic energy is conserved. Objects stick together after the elastic collision.

When the velocity of a mass on a spring is zero, the acceleration is at

Which is a disadvantage of using wind as an energy source? Check all that apply. It may be unreliable. It is not naturally occurring. It produces a lot of waste. It requires wires to carry electricity. It generates large amounts of electricity.