Changes In Momentum

Question 1

what happens when a resultant force acts on an object for certain amount of time

Answer 1

it causes a change in momentum

Question 2

what equation from newton displays how a resultant force on an object causes it to accelerate

Answer 2

force = mass x acceleration

Question 3

what equation using force shows that acceleration is just a change in velocity over a certain period of time

Answer 3

• force = mass x change in velocity / time

- f = m(v - u) /t

Question 4

why does the mass x change in velocity equal a change in momentum

Answer 4

• because a force applied to an object over any time interval will change the objects velocity
• whether that through be changing the direction of the object
• or changing its ‘speed’ through acceleration or deceleration

Question 5

what is the equation which shows that mass x change in velocity equals the change in momentum

Answer 5

• force = change in momentum / time

- F = (mv - mu) / t

Question 6

what are units for force, change in momentum and time

Answer 6

• force = N
• change in momentum = kg m/s
• time = s

Question 7

using the equation for change in momentum, what does a faster change in momentum directly imply

Answer 7

• that the force causing the change must be bigger
• as when t gets smaller (time)
• the force calculated will be bigger

Question 8

why is it more dangerous for a car crash to happen with cars going at faster speeds than at slower speeds

Answer 8

• at faster speeds, the change in momentum from the cars crashing and the forces acting in opposite direction is much larger
• considering the cars stop instantly when they crash
• leading to a much larger force acting on the bodies of the car when using the change in momentum equation

Question 9

how can you relate the cars crashing at higher and slower speeds to the equation for acceleration

Answer 9

• when the fast cars with a higher velocity crash, the change in velocity would be much larger
• for a given time for the fast and slow cars
• meaning the acceleration (or accurately deceleration) is much higher
• and because of f - ma, a larger force is needed to produce a larger acceleration
• so acceleration and change in momentum are pretty much proportional

Question 10

what kind of relationship do the equations for acceleration and change in momentum have and what equation ties them together

Answer 10

• they have a proportional relationship
• which is explained through f = ma
• showing that a lager acceleration, caused by a larger change in velocities, leads to a higher force produced
• and the change in momentum equation shows that a larger difference in momentum, highly determined by velocity, will also lead to a higher produced force