Understanding Forces and Motion

Which of the following is a scalar quantity?

• Velocity

• Force

• Mass

• Displacement

Answer explanation

Mass is a scalar quantity as it has only magnitude and no direction. In contrast, velocity, force, and displacement are vector quantities, which have both magnitude and direction.

Which of the following is a vector quantity?

• Speed

• Temperature

• Distance

• Acceleration

Answer explanation

Acceleration is a vector quantity because it has both magnitude and direction. In contrast, speed, temperature, and distance are scalar quantities, which only have magnitude.

Newton's First Law of Motion is also known as the law of:

• Acceleration

• Inertia

• Action and Reaction

• Gravitation

Answer explanation

Newton's First Law of Motion is known as the law of Inertia because it states that an object at rest stays at rest, and an object in motion stays in motion unless acted upon by an external force.

According to Newton's Second Law, the force acting on an object is equal to:

• Mass times velocity

• Mass times acceleration

• Mass times speed

• Mass times distance

Answer explanation

According to Newton's Second Law, the force acting on an object is defined as the product of its mass and acceleration (F = ma). Therefore, the correct answer is 'Mass times acceleration'.

Newton's Third Law states that for every action, there is:

• A greater reaction

• An equal and opposite reaction

• A lesser reaction

• No reaction

Answer explanation

Newton's Third Law states that for every action, there is an equal and opposite reaction. This means that forces always occur in pairs, with one force acting in one direction and the other force acting in the opposite direction.

Which of the following best describes equilibrium of forces?

• Forces are unbalanced

• Forces are balanced

• Only one force acts on the object

• Forces are in motion

Answer explanation

Equilibrium of forces occurs when forces are balanced, meaning the net force acting on an object is zero. This results in no change in motion, unlike unbalanced forces which cause acceleration.

What is the resultant force when two forces of 5 N and 10 N act in the same direction?

• 5 N

• 10 N

• 15 N

• 20 N

Answer explanation

When two forces act in the same direction, their magnitudes add up. Therefore, 5 N + 10 N = 15 N, making the resultant force 15 N.

What is the resultant force when two forces of 8 N and 3 N act in opposite directions?

• 5 N

• 11 N

• 8 N

• 3 N

Answer explanation

When two forces act in opposite directions, you subtract their magnitudes. Here, 8 N - 3 N = 5 N. Therefore, the resultant force is 5 N.

Which of the following is the correct unit for force in the SI system?

• Kilogram

• Newton

• Joule

• Metre

Answer explanation

The correct unit for force in the SI system is the Newton. It is defined as the force required to accelerate a one-kilogram mass by one meter per second squared.

If an object is in equilibrium, the sum of the forces acting on it is:

• Greater than zero

• Less than zero

• Zero

• Equal to its mass

Answer explanation

An object in equilibrium has no net force acting on it. This means the sum of all forces is zero, ensuring that the object remains at rest or in uniform motion. Therefore, the correct answer is zero.