Chapter 6

Question 1

If an object is stationary, what is the value of the resultant force?

Answer 1

0

Question 2

What 5 factors will any measurement have?

Answer 2

• Quantity
• Magnitude
• Unit
• Error
• Scalar or vector

Question 3

When can a measurement be a scalar?

Answer 3

When it just has a magnitude/amount

Question 4

When can a measurement be a vector?

Answer 4

When it has a magnitude and a direction

Question 5

How do you model a vector?

Answer 5

Using straight arrows with a direction

Question 6

When modelling a vector, why is the size and length of the arrow important

Answer 6

Because it indicates the magnitude as you must declare a scale

Question 7

How do you get a resultant force from parallel vectors?

Answer 7

Add them numerically

Question 8

How do you get a resultant force from anti-parallel vectors

Answer 8

Add them numerically

Question 9

How do you get a resultant force from perpendicular vectors?

Answer 9

Pythag or trig

Question 10

Define the principle of moments

Answer 10

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

Question 11

Define the principle of moments

Answer 11

For a system in equilibrium, the sum of clockwise moments = the sum of anti clockwise moments about any given point

Question 12

Define centre of mass

Answer 12

The centre of mass on a body is the point at which a single force on the body has no turning effect

Question 13

What must be satisfied in order to have a couple?

Answer 13

Must have 2 forces equal in size and in opposite direction

Question 14

A body is at rest and a force is used to disturb the body. What happens if the body returns to its original position?

Answer 14

It is stable

Question 15

A body is at rest and a force is used to disturb the body. What happens if the body doesn’t return to its original position?

Answer 15

It isn’t stable

Question 16

What must be true about the weight and the pivot if the system is to be in equilibrium

Answer 16

The weight is in line vertically with the pivot point

Question 17

What happens if the COM is above the pivot point in relation to stability?

Answer 17

The object is unstable

Question 18

What happens if the COM is below the pivot point in relation to stability?

Answer 18

The object is stable

Question 19

Define toppling

Answer 19

The system is tilted up to a balance point, then pushed a bit further and topples over

Question 20

What can you say if a system is in equilibrium?

Answer 20

The resultant force is 0, and the principle of moments applies (clock and anti clock are equal)

Question 21

What does a free body force diagram show?

Answer 21

Shows all the forces acting on a body

Question 22

When do you use a triangle of forces diagram?

Answer 22

When funding the value of the forces or the resultant force