Scalars And Vectors

Question 1

What is a scalar?

Answer 1

A scalar is a physical quantity that needs a magnitude and a unit

Scalars do not have direction associated with them.

Question 2

What is a vector?

Answer 2

A vector is a physical quantity that needs a magnitude, a direction and a unit

Vectors are essential for describing quantities that have direction.

Question 3

List 10 examples of scalar quantities

Answer 3

• Distance
• Speed
• Rate of change of speed
• Mass
• Time
• Temperature
• Kinetic energy
• Electric charge
• Area
• Volume

Scalars are often used in physics to describe measurements without direction.

Question 4

List 6 examples of vector quantities

Answer 4

• Displacement
• Velocity
• Acceleration
• Force
• Momentum
• Electric current

Vectors are crucial in physics for describing motion and forces.

Question 5

Answer 5

Question 6

Answer 6

Question 7

Answer 7

Question 8

Answer 8

Question 9

Define the moment of a force about a point

Answer 9

The moment of a force about a point is defined as the product of the force and the perpendicular distance from the point to the line of action of the force

The moment is a measure of the tendency of a force to cause rotation about a point.

Question 10

Write the equation used to calculate the moment of a force

Answer 10

M = F x d

M represents the moment, F is the force applied, and d is the perpendicular distance from the point to the line of action of the force.

Question 11

Write what the letters in the moment equation stand for

Answer 11

• M = Moment (Nm)
• F = Force (N)
• d = Perpendicular distance from pivot (m)

Each variable must be in its respective SI unit for the equation to be valid.

Question 12

What is the centre of gravity of an object?

Answer 12

The point at which we take its weight to act

The centre of gravity is crucial for understanding how an object will balance and behave under the influence of forces.

Question 13

What is the centre of mass of an object?

Answer 13

The point at which we take its mass to be concentrated

The centre of mass is important in physics as it simplifies the analysis of motion and forces acting on an object.

Question 14

State the principle of moments

Answer 14

When an object is in rotational equilibrium, the sum of the clockwise moments about any point is equal to the sum of the anticlockwise moments about the same point

This principle is fundamental in understanding balance and stability in static systems.

Question 15

If an object is in equilibrium, what two things must be true?

Answer 15

• There is no resultant force in any direction
• There is no net turning effect about any point

These conditions ensure that the object remains at rest or continues to move at a constant velocity.