Mechanics

Question 1

Equilibrium

Answer 1

Forces are balanced
Moments are balanced

Question 2

Newton’s 1st Law

Answer 2

If the sum of forces = 0 or noexternal resultant forces act on a body, a body will remain at rest or continue moving with constant velocity.

Question 3

Principle of Moments

Answer 3

For a system to be in equilibrium, the total clockwise moments about a point must equal the total anticlockwise moments about the same point

Question 4

Conservation of Energy

Answer 4

In a closed system, total energy is constant. Energy cannot be created or destroyed, only transferred.

Question 5

Conservation of Momentum

Answer 5

In a closed system (no external resultant force acts on the system), total momentum remains constant

Question 6

Elastic Collision

Answer 6

Momentum and Ek are conserved

Question 7

Inelastic Collision

Answer 7

Momentum is conserved but some Ek has been “lost” (converted to another form of energy e.g. heat)
Total Energy is always conserved

Question 8

Totally Inelastic Collision

Answer 8

The colliding objects stick together after the collision (impossible to conserve Ek)