3. It takes at least 4 people to push a refrigerator up a 10-meter ramp. How many people would be needed to push the same refrigerator to the same height using a 20-meter ramp? (Assume no friction for both ramps.)
O A. at least 2 people
O B. at least 4 people
O c. at least 8 people
D. Not enough information (could be impossible).
.

Aray of light traveling parallel to the principal axis of a concave mirror will be reflected through the mirror's

Your starship, the aimless wanderer, lands on the mysterious planet mongo. as chief scientist-engineer, you make the following measurements: a 2.50-kg stone thrown upward from the ground at 14.0 m/s returns to the ground in 5.70 s ; the circumference of mongo at the equator is 2.20×10^5 km ; and there is no appreciable atmosphere on mongo. (a) the starship commander, captain confusion, asks for the following information: what is the mass of mongo? (b) if the aimless wanderer goes into a circular orbit 2.20×10^4 km above the surface of mongo, how many hours will it take the ship to complete one orbit? (c) an unmanned spacecraft is in a circular orbit around the moon, observing the lunar surface from an altitude of 44.0 km . to the dismay of scientists on earth, an electrical fault causes an on-board thruster to fire, decreasing the speed of the spacecraft by 23.0 m/s . if nothing is done to correct its orbit, with what speed (in km/h) will the spacecraft crash into the lunar surface?

The strong nuclear force acts over a small distance than the electrostatic force. true or false