Although the gravitational force the Earth exerts on the objects is different, their masses are just as different, so the effect we observe (acceleration) is the same for each. The Earth’s gravitational force accelerates objects when they fall. It constantly pulls, and the objects constantly speed up.

The main features of the solar system

• The Sun is our nearest star .
• The planets orbit the Sun.
• The time taken to orbit the Sun increases with distance from the Sun.
• Gravity keeps the planets in orbit around the Sun and the moons in orbit around their planets.

The Solar System moves through the galaxy with about a 60° angle between the galactic plane and the planetary orbital plane. The Sun appears to move up-and-down and in-and-out with respect to the rest of the galaxy as it revolves around the Milky Way.

There are two forces that keep the planets in their orbits.

• Gravity. Gravity is the primary force that controls the orbit of the planets around the sun.
• Inertia.
• Gravity Working with Inertia.
• Velocity and Gravity.

Objects change their motion because unbalanced forces act on them. There are four main factors that affect the motion of objects. These factors are force, friction, inertia, and momentum.

The second law states that the acceleration of an object is dependent upon two variables – the net force acting upon the object and the mass of the object. The acceleration of an object depends directly upon the net force acting upon the object, and inversely upon the mass of the object.

balanced forces do not affect the motion of the object. Unbalanced forces affect the motion and velocity of an object. If forces are in the same direction, how would you calculate net force? If forces are in opposite directions, how would you calculate net force?

Motion requires force, because as we say in the song, Inertia is a property of matter. Inertia is the tendency for any moving object to keep moving and any object at rest to remain at rest.

Inertia is that quantity which depends solely upon mass. The more mass, the more inertia. Momentum is another quantity in Physics which depends on both mass and speed.

Friction is a force that occurs when two surfaces slide past one another. The force of friction opposes the motion of an object, causing moving objects to lose energy and slow down. When objects move through a fluid, such as air or water, the fluid exerts a frictional force on the moving object.

types of motion. Motion may be divided into three basic types — translational, rotational, and oscillatory.

Friction is determined by the two surfaces in contact, and how tightly the two surfaces are pushed together (normal force F N F_N FN​F, start subscript, N, end subscript). Coefficient of friction ( μ): this describes the roughness between two surfaces. A high coefficient of friction produces more friction.

Answer: Forces can give energy to an object and cause it to move, forces can stop the movement of an object, and forces can change the direction of an object. Friction is a force that opposes motion. When two objects are in contact, friction is acts in a direction opposite to the motion of the object.

The action from a force can cause an object to move or speed up (accelerate), to slow down (decelerate), to stop, or to change direction.

The force of friction (which is always present on Earth) can keep an object stationary or can slow it down once it is moving. FRICTION: Friction is a force that opposes motion. When two objects are in contact, friction is acts in a direction opposite to the motion of the object.

When we walk, our feet are pushing backwards and therefore the friction opposes the pushing and acts in the opposite direction which happens to be the direction in which we are walking.

In any type of vehicle—such as a car, boat or airplane—excess friction means that extra fuel must be used to power the vehicle. In other words, fuel or energy is being wasted because of the friction. Fluid friction or air resistance can greatly reduce the gas mileage in an automobile.

First law of friction: The amount of friction is proportional to the normal force exerted between the surfaces. Second law of friction: Friction does not depend on the area of contact between the object and the surface. Third law of friction: Friction force also depends on the nature of the surfaces in contact.

Friction can be useful. friction between our shoes and the floor stop us from slipping. friction between tyres and the road stop cars from skidding. friction between the brakes and wheel help bikes and cars to slow down.