Motion 3

Question 1

state Newton’s three laws of motion

Answer 1

1: an object either remains at rest or continues to move at a constant velocity, unless acted upon by a force
2: the net force on an object is proportional to its rate of change of momentum (mv-mu)/Δt
3: if body A causes a force on body B, there is an equal and opposite reaction force on body A

Question 2

define linear momentum

Answer 2

mass x velocity (kgm/s)

Question 3

state the special property of momentum

Answer 3

momentum is always conserved before and after a collision

Question 4

is momentum a vector or a scalar quantity

Answer 4

vector. horizontal momentum is always conserved and vertical momentum is always conserved

Question 5

define net force

Answer 5

Δp/Δt (rate of change of momentum)

Question 6

define impulse and state the condition for it being called impulse

Answer 6

Δp=FΔt
impulse is momentum, but usually over very short time scales
if the timescale of impact is the same for both objects, their impulses are equal and opposite because of Newton’s third law

Question 7

what is the area under a force-time graph

Answer 7

impulse

Question 8

define

• a perfectly elastic collision

- an inelastic collision

Answer 8

an elastic collision is one where all of the kinetic energy is conserved
an inelastic collision is one where some of the kinetic energy is converted into other forms, such as thermal