How many planets are in the sky

Friction in machines is commonly reduced by using what?

When Maggie applies the brakes of her car, the car slows uniformly from 15.3 m/s to 0 m/s in 2.23 s. How far ahead of a stop sign must she apply her brakes in order to stop at the sign? Answer in units of m

A 16.0 m long, thin, uniform metal rod slides north at a speed of 21.0 m/s. The length of the rod maintains an east-west orientation while sliding. The vertical component of the Earth's magnetic field at this location has a magnitude of 42.0 µT.

A baseball is thrown home plate at 40m/s ... the batter hits the ball and sends it flying at 60 m/s in the opposite direction. If this hit only took 0.01 seconds, then the acceleration of the ball is

A 75 kg person walking around a corner bumped directly into an 80 kg person who was running around the same corner. The momentum of the 80 kg person.

Which of the following simple machines includes a wedge? A. axe B. file C. bolt D. ramp

What are the units of speed or velocity

List the colors of visible light in order of decreasing frequency physics

You can identify a pure substance if you know it's?

A rod of mass M and length L can rotate about a hinge at its left end and is initially at rest. A putty ball of mass m, moving with speed V, strikes the rod at angle θ from the normal and sticks to the rod after the collision.