how much force does the motor of an elevator need to exert to hold a 1000 kg elevator still if the counterweight weighs 7000 newtons?

Suppose two stars are located in region a of the h-r diagram shown in the figure below. Star X appears much dimmer that Star Y as seen from Earth. Which Star can be inferred to be nearer to Earth, and how do you know?

The relationship between frequency, wavelength, and speed holds for light waves because A. light travels slower in a vacuum than in air B. all forms of electromagnetic radiation travel at a single speed in a vacuum C.

If such drivers are traveling on a straight road at 30 mph (44 ft/s) and their cars can decelerate at 27 ft/s², determine the shortest stopping distance d for a normal driver from the moment he or she see the pedestrians.

You increase your walking speed from 1m/s to 3m/s in a period of 1 s. What is your acceleration

True or false nodes and antinodes occur in longitudinal waves

Which of Newton's laws, when combined algebraically with his law of universal gravitation, can be used to calculate Earth's mass? A) first B) second C) third

Why does a balloon filled with helium rise while a balloon filled with an equal volume of average atmospheric air does not? A. Helium has no mass, but air does. B. Helium increases the balloon's mass more than air. C.

Consider the following controls in an automobile in motion : gas pedal, brake, steering wheel. what are the controls in this list that cause an acceleration of the car?

What material are oil pipelines made from?

3/129 A 175-lb pole vaulter carrying a uniform 16-ft, 10-lb pole approaches the jump with a velocity v and manages to barely clear the bar set at a height of 18 ft. As he clears the bar, his velocity and that of the pole are essentially zero.