Module 3

Question 1

Centre of gravity

Answer 1

Single point where the entire weight of the abject acts

Question 2

Archemides principle

Answer 2

Object submerged in a fluid has upward force (UPTHRUST) equal to the weight of fluid displaced by the object

Question 3

Describe how centre of gravity can be determined (4 marks)

Answer 3

Allow object to hang freely from a hole near the edge
Draw vertical line downwards using plumb line
Repeats for at least one more whole
Where lines intersect is centre of gravity

Question 4

N 1st law

Answer 4

Body will remain at rest or constant velocity/current sate of motion unless an external force acts on it

Question 5

N 3rd law

Answer 5

Every action has equal and opposite reaction

Question 6

N 2nd law

Answer 6

Net force is equal to rate of change of momentum of the object

Question 7

Moment

Answer 7

Product of force and perpendicular distance from pivot

Question 8

Principe of moment

Answer 8

Sum of clockwise moment = sum of anticlockwise moments
In equilibrium

Question 11

Describe how KE of arrow changed from beginning of journey to max height

Answer 11

• KE decreases as height increases
• At max height KE at minimum

Question 12

Inertia

Answer 12

How difficult it is to change velocity of an object