M87, located just under 55 million light-years from the Milky Way, was chosen for humanity's first image of the shadow of a ...

Emergent gravity is a bold idea. It claims that the force of gravity is a mere illusion, more akin to friction or heat—a ...

Ice causes very little friction, which is why it is easy to slip over on an icy day. However, this is a good thing for ice skating and sledging. Friction is a force between two surfaces that are ...

Friction is a force that opposes motion. It is present whenever two surfaces rub over each other, such as when you rub your hands together, or when you apply the brakes on a bike or in a car.