Does the mass of an object ever change

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How much work does the force of gravity do in pulling a 10 kg box down a 30º inclined plane of length 8.0 m? Note that sin 30 = cos 60 = 0.500 and cos 30 = sin 60 = 0.866. Can someone explain this one?

Is a liter the same as a cubic meter

A swimmer runs over a horizontal diving board at a speed of 0.95 meters/second. 2.0 seconds after she dives, she hits the water.

What does invading the host cell enable the virus to do? A) increase its size B) synthesize needed oxygen C) obtain nutrients D) reproduce

Conduction occurs more easily between solids and liquids. This is because the particles in gases are A) farther apart and move faster. B) closer together and move faster. C) further apart and move more slowly. D) closer together and move more slowly.

Which statement best compares the accelerations of two objects in free fall? O The heavier object has a greater acceleration.

A series RCL circuit includes a resistance of 280, an inductive reactance of 508, and a capacitive reactance of 315. The current in the circuit is 0.312 A.

A ray in benzene has a critical angle of 41.8 deg when trying to enter air. What is the index of refraction for benzene?

An elevator has mass 600 kg, not including passengers. the elevator is designed to ascend, at constant speed, a vertical distance of 20.0 m (five floors) in 16.0 s, and it is driven by a motor that can provide up to 40 hp to the elevator.

When two objects collide and stick together, what will happen to their speed, assuming momentum is conserved? They will move at the same velocity as whichever object was fastest initially.