Physical Processes - Forces In Action

Friction and weight are both forces that act on objects. Friction is the force that opposes the motion of an object when it is in contact with another surface, while weight is the force exerted on an object due to gravity. However, height is not a force. Height is a measurement of distance and does not have the ability to exert a force on an object.

The pavement exerts an equal force in the opposite direction. This is known as the normal force, which is a contact force exerted by a surface to support the weight of an object resting on it. When you stand on the pavement, the pavement pushes back against you with an equal force, preventing you from falling through. This is why you don't fall through the pavement even though gravity pulls you towards the center of the Earth.

The Earth is the correct answer because it has a much larger mass compared to the moon. The force of gravity is directly proportional to the mass of an object, so the greater the mass, the greater the gravitational force. Therefore, you would feel heaviest on Earth due to its stronger gravitational pull.

Gravity is a force that attracts objects towards the center of the earth. This force is present everywhere, whether it is in air, water, or on land. It acts on all objects, including aeroplanes flying in the sky. Therefore, the statement "Gravity always acts towards the centre of the earth" is true.

When an object falls, it experiences the force of gravity pulling it downward, which is known as its weight. At the same time, the object also experiences air resistance, which is a force exerted by the air in the opposite direction to the object's motion. This air resistance acts in the opposite direction to the weight, slowing down the object's fall. Therefore, the correct answer is that air resistance acts in the opposite direction to the weight.

Weight is a force that is measured in Newtons. Newtons is the standard unit of force in the International System of Units (SI). It is named after Sir Isaac Newton, who formulated the laws of motion. Weight is the force exerted on an object due to the gravitational pull of the Earth or any other celestial body. The magnitude of this force is measured in Newtons, which is equal to the mass of the object multiplied by the acceleration due to gravity.

When an object is at rest or stationary, it means that it is not moving. However, this does not mean that there are no forces acting on it. In fact, there can be forces acting on the object, but these forces are balanced. This means that the forces are equal in magnitude and opposite in direction, resulting in a net force of zero. As a result, the object remains at rest and does not move.

When an object is suspended in water, it experiences an upward buoyant force equal to the weight of the water displaced by the object. This buoyant force reduces the effective weight of the apple, resulting in a smaller reading on the forcemeter compared to when the apple is suspended in air. Therefore, an apple suspended in water gives the smallest reading on a forcemeter.

When the girl stands still holding a racket on a tennis court, her weight acts downwards due to gravity. At the same time, a reaction force from the ground acts upwards to balance her weight. These two forces are balanced because the upward reaction force from the ground cancels out the downward force of her weight, allowing her to maintain her position on the tennis court.

This statement is false because a moving object does not necessarily travel in a straight line until a force changes its direction. In reality, a moving object can change its direction without the application of any external force, such as when it moves in a curved path due to inertia or gravitational forces. Therefore, the statement contradicts the concept of objects moving in curved paths without the need for external forces.