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1.
Define momentum. |
Answer
Momentum is defined as being the product of the mass of an object and it’s velocity, or the ‘quantity of motion’. |
2. Is momentum a vector or a scalar quantity? |
Answer
Vector You must provide a direction as well in your final answer. |
3.
A trolley X of mass 6kg has a velocity of 4ms^{-1} east. Calculate it’s momentum. |
Answer
p = mv p = 6(4) p = 24kg.m.s^{-1} east |
4. Calculate the change in momentum of a 3kg trolley if the velocity of the trolley increased from 5ms^{-1} east to 7ms^{-1} east. |
Answer
Δp = m(v_{f} - v_{i}) Δp = 3(7 - 5) Δp = 6kg.m.s^{-1} east |
5. Calculate the change in momentum of a 5kg trolley if the velocity of the trolley changed from 8ms^{-1} east to 12ms^{-1} west. |
Answer
Choose final direction as positive Thus west is positive, and east is negative.
Δp = m(v_{f} - v_{i}) |
6. A force of 4N acts west on a trolley for 3s. Calculate the impulse exerted on the trolley. |
Answer
Δp is also called IMPULSE Δp can also be calculated from:
Δp = FΔt |
7. The velocity of a 2kg trolley changed from 4ms^{-1} east to 7ms^{-1} east over a period of 10s. Calculate the force that must have been used. |
Answer
Since Δp = m(v_{f} - v_{i}) and Δp = FΔt
FΔt = m(v_{f} - v_{i}) |
8. An arrow of mass 250g strikes a wooden block with a velocity of 80ms^{-1} east and is brought to a halt in 0,8s. Calculate the stopping force. |
Answer
m = 0,25kg v_{f} = 0 (stopped) positive = east
FΔt = m(v_{f} - v_{i}) |
9.
The rate of change of momentum is equivalent to :
A. impulse |
Answer
B. force
FΔt = Δp |
10.
A body of mass m strikes a wall perpendicularly with a speed of v and bounces directly back with no change in its speed. The change in its momentum would be:
A. zero |
Answer
C. 2mv two directions = two signs Let final velocity = v Then initial velocity = -v
Δp = m(v_{f} - v_{i}) |