Why are the horinzontal forces acting on the book balanced

How did the theory of plate tectonics come to be a theory?

The number of neutrons in an atom equals to the? ...

If you do not have oil in your car's engine, the parts that rub together in the engine get very hot. What does the oil do? A. It decreases the force of gravity. B. It increases the force of gravity. C. It decreases the force of friction. D.

A person measures his heart rate by counting the number of beats in 30 s. if 33 ± 2 beats are counted in 30.0 ± 0.4 s, what is the heart rate and its uncertainty in beats per minute?

What current would it need to carry in order to experience a very modest 1.0*10-3n⋅m torque?

When distances were carefully measured from Earth to globular clusters above and below the Milky Way plane (where our view of them is not obscured by interstellar dust and gas), their distribution was found to be

Imagine you transfer heat into a gas. This heat splits up in two different ways: Additional thermal energy making the gas hotter and "fuel" for the gas to do work. Let's suppose, 64% of the transferred heat transforms into thermal energy.

How much heat is absorbed by a 61g iron skillet when its temperature rises from 5oC to 29oC?

Explain the relationship between motion and frame of reference.

Two students are looking at a brightly lit full Moon, illuminated by the reflected light from the Sun. Consider thefollowing discussion between the two students about what the spectrum of moonlight would look like.