Physics Quiz: Basic Exam MCQ!

Momentum is defined as the product of an object's mass and velocity. This means that in order for momentum to exist, both mass and velocity must be present. Mass represents the amount of matter in an object, while velocity represents the object's speed and direction. Without either of these factors, momentum cannot be calculated or observed. Therefore, mass and velocity are the necessary factors for momentum to be possible.

Momentum is defined as the product of an object's mass and velocity. It is a vector quantity, meaning it has both magnitude and direction. Momentum is a measure of how difficult it is to stop an object's motion. The greater the mass and velocity of an object, the greater its momentum. Therefore, momentum is the correct answer as it directly relates to the product of mass and velocity.

Acceleration is the rate at which an object's velocity changes over time. It is a measure of how quickly an object's speed or direction changes. In other words, acceleration is the change in velocity per unit time. It can be positive or negative, depending on whether the object is speeding up or slowing down. Therefore, acceleration is the correct answer to the given question.

The average velocity of an object is calculated by taking the total displacement and dividing it by the total time taken. In this case, since the initial and final velocities are given, we can assume that the bus is moving with a constant velocity. Therefore, the average velocity would be equal to the final velocity, which is 40 m/s.

The correct answer is thermal pollution. Thermal pollution refers to the harmful effects on the environment caused by the release of heat into the environment by heat engines and refrigerators. This is a consequence of their low thermal efficiency, as a significant amount of heat is wasted and released into the environment. This excess heat can disrupt ecosystems, harm aquatic life, and contribute to global warming.

During an elastic collision, the total kinetic energy of the system remains constant. This means that no energy is lost or converted into other forms such as heat. Additionally, the colliding objects bounce off each other after the collision. Therefore, the correct answer is "elastic" because it satisfies both conditions of the total kinetic energy remaining constant and the objects bouncing off.

In a refrigerator, the energy transformation that takes place is from electrical energy to mechanical energy. This is because the refrigerator uses an electric motor to compress the refrigerant gas, which in turn generates mechanical energy to circulate and cool the air inside the refrigerator.

The product of force and time is equal to the change in momentum. This concept is known as impulse. Impulse can be defined as the change in momentum of an object, which occurs when a force is applied to it for a certain period of time. In other words, impulse measures the impact of a force on an object, taking into account both the magnitude of the force and the duration of its application. Therefore, impulse is the correct answer in this context.

The faster car has greater momentum because momentum is directly proportional to an object's mass and velocity. Since the two cars are identical in mass, the car with greater velocity will have greater momentum.

When there is no change in both direction and velocity, the acceleration is zero. This means that the object is either at rest or moving with a constant speed in a straight line. In this case, there is no acceleration because there is no change in the object's velocity over time.