Understanding Forces and Motion

What is the term used to describe the change in position of an object?

• Speed

• Displacement

• Velocity

• Acceleration

Answer explanation

Displacement refers to the change in position of an object, measuring the shortest distance from the initial to the final position, while speed, velocity, and acceleration describe different aspects of motion.

Which of the following is a vector quantity?

• Speed

• Distance

• Velocity

• Time

Answer explanation

Velocity is a vector quantity because it has both magnitude and direction, unlike speed and distance, which are scalar quantities. Time is also a scalar and does not have direction.

What is the force that opposes the motion of objects in contact?

• Gravity

• Friction

• Normal force

• Elastic force

Answer explanation

Friction is the force that opposes the motion of objects in contact. It acts parallel to the surfaces in contact, resisting their relative motion, making it the correct answer to the question.

According to Newton's first law of motion, an object at rest will stay at rest unless acted upon by a:

• Balanced force

• Unbalanced force

• Gravitational force

• Normal force

Answer explanation

According to Newton's first law, an object at rest remains at rest unless acted upon by an unbalanced force. This means that only an unbalanced force can change the state of motion of the object.

What is the term for the force exerted by a surface perpendicular to an object resting on it?

• Gravitational force

• Frictional force

• Normal force

• Tension force

Answer explanation

The normal force is the support force exerted by a surface that is perpendicular to the object resting on it. It counteracts the weight of the object, distinguishing it from gravitational, frictional, and tension forces.

Which of the following describes the rate of change of velocity?

• Speed

• Displacement

• Acceleration

• Force

Answer explanation

Acceleration describes the rate of change of velocity, indicating how quickly an object's speed or direction changes over time. Speed measures how fast an object moves, while displacement refers to the change in position.

What is the net force acting on an object if it is moving at a constant velocity?

• Greater than zero

• Less than zero

• Zero

• Equal to its weight

Answer explanation

When an object moves at a constant velocity, it means there is no acceleration. According to Newton's first law, if the net force is zero, the object will maintain its state of motion, confirming that the net force is indeed zero.

Which of the following is an example of a noncontact force?

• Friction

• Tension

• Gravitational force

• Normal force

Answer explanation

Gravitational force is a noncontact force because it acts at a distance, attracting objects without physical contact. In contrast, friction, tension, and normal force require direct contact between objects.

What is the term for the force that acts in pairs according to Newton's third law of motion?

• Contact force

• Force pairs

• Net force

• Elastic force

Answer explanation

According to Newton's third law of motion, forces always occur in pairs, known as force pairs. This means that for every action, there is an equal and opposite reaction, making 'force pairs' the correct term.

What is the formula for calculating weight?

Answer explanation

The correct formula for calculating weight (W) is W = m · g, where m is mass and g is the acceleration due to gravity. This formula shows that weight is directly proportional to mass and the gravitational force acting on it.