In a magnet, like poles repel and unlike poles attract.

The force between two magnets or the force between a magnet and another magnetic material is known as magnetic force.

Gravity is a universal, non-contact force. Everything stays on the surface of the Earth due to its gravitational force. 

Kinetic energy is the energy possessed by a body or an object because of it's motion.
Example: A ball rolling on the floor has kinetic energy because of its motion.

The like poles of magnets repel and unlike poles attarct each other. This is the reason why bringing the like poles of two magnets close makes them repel each other. 

The application of force on a body can change the shape of the body. The shape of the spring changes when we apply force on it.

The work done is directly proportional to the displacement. Hence, the work done will be maximum when a bag is carried for 10 km.

The energy possessed by a body due to its position is known as potential energy.

Water reduces friction on the water slides. Hence, we move faster on water slides as there is less friction.