What is the efficiency of a device that takes 400J of heat and does 120J of work while giving off 280 J of heat

A person jogs eight complete laps around a 400-m track in a total time of 14.5 min. Calculate the average speed and the average velocity in m/s

If an object is traveling along at a constant velocity and there is friction acting on the object, what can be concluded about the forces acting on this object?

John knows that the atomic number of the element Chlorine, Cl, is 17. He also knows that one particular isotope of chlorine has a mass of 35. How many neutrons can be found in the nucleus of this isotope of chlorine?

Unlike gases, water exerts no pressure. If there's a structural problem on a submarine, the submarine is not likely to be crushed as it descends. True or False?

A white dwarf in a binary system suddenly flares, but in a few months it settles back to its original luminosity. This process may repeat many times. What object is it?

What causes day and night on earth?

A yo-yo can be thought of as a solid cylinder of mass m and radius r that has a light string wrapped around its circumference (see below). One end of the string is held fixed in space.

Why is time an independent variable and position is a dependent variable in a position versus time graph

A geologist estimates that a large boulder weighs 7840 N. What should he estimate the mass of this boulder to be? A. 650 kg B. 740 kg C. 780 kg D. 800 kg

Two objects have the same momentum. Do the velocities of these objects necessarily have (a) the same directions and (b) the same magnitudes? Give your reasoning in each case.