Motion And Forces Pre-test

A barometer measures atmospheric pressure. Atmospheric pressure refers to the force exerted by the weight of the air in the atmosphere. Barometers are commonly used to determine changes in weather patterns as variations in atmospheric pressure can indicate the approach of high or low-pressure systems. By measuring atmospheric pressure, barometers help in forecasting weather conditions and understanding atmospheric phenomena.

The given scenario describes Newton's first law of motion, also known as the law of inertia. According to this law, an object at rest will remain at rest unless acted upon by an external force. In this case, the rock is initially at rest, and it starts moving when someone applies a force by pushing it. This behavior aligns with Newton's first law, making it the correct answer.

Inertia is the tendency of an object to resist changes in its motion. This means that an object at rest will stay at rest, and an object in motion will continue moving at a constant velocity unless acted upon by an external force. Inertia depends on the mass of the object, as objects with more mass have more inertia and are more resistant to changes in motion.

When an object's weight is greater than its buoyant force, the object will sink. This is because the buoyant force is the upward force exerted by a fluid on an object immersed in it. If the weight of the object is greater than the buoyant force, the object will not experience enough upward force to counteract its weight, causing it to sink.

The law of conservation of momentum states that the total momentum of a group of objects remains constant unless outside forces act on the group. This means that in the absence of external forces, the total momentum of the objects involved in a system will not change. This principle is based on the idea that momentum is a conserved quantity, meaning it cannot be created or destroyed, only transferred or redistributed within a system.

The equation for speed is given by s=d/t, where s represents speed, d represents distance, and t represents time. This equation shows that speed is equal to the distance traveled divided by the time taken to travel that distance.

The force of gravity exists between two objects with mass. Gravity is a fundamental force of nature that attracts objects with mass towards each other. This force is directly proportional to the mass of the objects and inversely proportional to the square of the distance between them. Therefore, for gravity to exist, both objects must have mass. If one or both objects are weightless (meaning they have negligible mass), the force of gravity would be negligible or non-existent.

An object's velocity does not change due to balanced forces. Balanced forces do not cause any change in the motion of an object. When the forces acting on an object are balanced, the object will either remain at rest or continue to move at a constant velocity. A change in velocity occurs when unbalanced forces act on an object, causing it to accelerate or decelerate.

The statement "Buoyant force changes with depth" is false. According to Archimedes' principle, the buoyant force experienced by an object submerged in a fluid is equal to the weight of the fluid displaced by the object. This buoyant force remains constant regardless of the depth of the object in the fluid. Therefore, the buoyant force does not change with depth.