Basic Physics Practice Quiz

The Newton is the SI unit of force because it directly relates to mass and acceleration as defined by Newton's second law. The other units represent different physical quantities, such as energy, power, or pressure.

Newton's Second Law of Motion states that force equals mass multiplied by acceleration (F = m Ă - a). This equation clearly defines the relationship between force, mass, and acceleration, unlike the other options which are mathematically incorrect.

Kinetic energy is given by the formula ½mv², meaning it depends on both the mass of the object and the square of its velocity. The other options involve factors not directly related to kinetic energy.

Work is defined as the application of force over a displacement in the direction of that force (Work = Force Ă - Distance). This distinguishes work from other concepts such as energy or power.

Gravity is the force of attraction that acts between any two masses, drawing them toward each other. It is a fundamental force in physics and is distinct from other concepts like energy or speed.

Using the kinetic energy formula KE = ½ m v², substitute m = 1500 kg and v = 20 m/s to obtain ½ à - 1500 à - (20²) = 300,000 Joules. The other options arise from common calculation errors.

In an isolated system where no external forces act, the principle of conservation of momentum applies, meaning total momentum before and after collision remains the same. Kinetic energy, however, might not be conserved especially in inelastic collisions.

The slope of a displacement-time graph indicates the rate at which displacement changes over time, which is the definition of velocity. A constant slope corresponds to constant velocity, while changes in the slope indicate acceleration.

An object in free fall near Earth's surface accelerates downward at approximately 9.8 m/s² due to gravity. The other options either reverse the direction or incorrectly double the acceleration.

In the equation for gravitational force, r represents the distance between the centers of the two masses. This distance is squared in the denominator, indicating that the force decreases rapidly as the separation increases.

Work is calculated as the product of force and displacement (Work = Force Ă - Distance). Therefore, 10 N multiplied by 5 m gives 50 Joules of work done.

Potential energy is the energy stored within an object due to its position, configuration, or state. It is distinct from kinetic energy, which is the energy of motion.

Gravitational force is directly proportional to the mass of the object, meaning that as mass increases, the gravitational force increases as well. This is a key component in Newton's law of universal gravitation.

Inertia is a measure of an object's resistance to changes in its motion, and it is quantified by mass. The larger the mass, the greater the inertia, regardless of the object's weight or speed.

Air resistance acts as a force that opposes the motion of a falling object, thereby reducing its net acceleration compared to free fall. This is why objects eventually reach terminal velocity when falling through the atmosphere.

A collision where the two objects stick together is known as a perfectly inelastic collision. In such collisions, momentum is conserved even though some kinetic energy is lost as other forms of energy.

The principle of conservation of energy states that the total energy in an isolated system remains constant; it can neither be created nor destroyed, only transformed. This fundamental concept applies to all types of energy conversions.

In a hydroelectric power plant, water stored at height (potential energy) flows downward (kinetic energy) and drives turbines to produce electrical energy. This multi-stage energy conversion is a classic example of energy transformation in renewable energy systems.

Friction is the resistive force that acts opposite to the direction of motion when two surfaces are in contact. Its magnitude depends on the surfaces involved and the normal force between them, hence it always works against the motion.

At the peak of its upward trajectory, the ball momentarily has zero vertical velocity; however, gravity continues to accelerate it downward at approximately 9.8 m/s². This constant acceleration is the reason the ball eventually begins its descent.