Tutorial and Examples
Momentum can be described as the sum product of the mass of an object and its velocity. This means that momentum measures the force produced by an object’s mass and velocity.
The formula for calculating momentum is =
Momentum = mass X velocity
P = MV
Where P = momentum, V = velocity and M = mass
Based on the above definition, it is clear that the momentum of a car and a bicycle both travelling at 20 m/s will not be the same, because although the velocity of the two objects are the same, their mass is different. The car would have greater momentum, due to its larger mass.
The SI unit for velocity = m/s
SI unit for Mass = kg
So therefore momentum = kg x m/s and SI unit for momentum is kg x m/s
Momentum must always have a direction and so the final answer must reflect the direction of the momentum or velocity.
1. Find the momentum of a round stone weighing 12.05kg rolling down a hill at 8m/s.
Formula – P= kg x m/s
= 12.05kg x 8m/s
= 96.4 kg x m/s down hill
Note that the final answer has the proper SI unit of momentum (kg x m/s) after it and it also mentions the direction of the movement.
2. A cannon ball weighing 35kg is shot from a cannon towards the east at 220mls, calculate the momentum of the cannon ball.
Formula – P= kg x m/s
= 35kg x 220m/s
= 7700 kg x m/s east
Momentum questions generally appear with general science and/or basic physics. Tests with momentum questions:
1. Three cars are travelling down an even road at a velocity of 110 m/s, calculate the car with the highest momentum if they are all moving at the same speed, but the first car weighs 2500kg, second car weighs 2650kg and third car weighs 2009kg?
a. First car
b. Second car
c. Third car
d. All have same momentum
2. What is the momentum of a log of wood that weighs 700kg rolling down a hill at 4.6m/s.
a. 3320 kg x m/s down hill
b. 3320 kg x m/s
c. 3320 down hill
d. 3320 M
3. An object that weighs 500g is rolling along the road at 3.5m/s, what is the momentum of the object?
a. 124.9 kg x m/s along road
b. 17. 50 kg x m/s along road
c. 1750 kg x m/s along road
d. 1.75 kg x m/s along road
4. A javelin is thrown into a field at 18m/s. if the Javelin weighs 1.5kg, what is the momentum?
a. 1.2 kg x m/s into the field
b. 12 kg x m/s into the field
c. 27 kg x m/s into the field
d. 2.7 kg x m/s into the field
5. Which of these object has greater momentum, a 2kg truck moving east at 3.5m/s or a 4.3kg truck moving south at 1.5m/s?
a. First truck at 7 kg x m/s moving east
b. Second truck at 7.45 kg x m/s due south
c. First truck at 6.45 kg x m/s due east
d. Second truck at 7 kg x m/s due south
6. A bullet weighing 350g is shot towards a target at a velocity of 250m/s. Calculate the momentum of the bullet
a. 1.4 kg x m/s towards target
b. 87.5 kg x m/s towards target
c. 87500 kg x m/s towards target
d. 8.75 kg x m/s towards target
Momentum is a product of velocity and mass. If they are all traveling at the same speed, the car that weighs the most would have the highest momentum.
4.6 X 700 = 3220 down the hill
First convert 500g to kg = 500/1000 = 0.5kg, momentum = 0.5 x 3.5 = 1.75 kg x m/s along the road.
p = 1.5 x 18 = 27 kg x m/s into the field.
The momentum of first object = 2 x 3.5 = 7; momentum of second truck = 4.3 x 1.5 = 6.45. First truck has more momentum at 7 kg x m/s moving east.
First convert 350g to kg = 350/1000 = 0.35kg. Momentum of bullet = 0.35 x 250 = 87.5 kg x m/s towards target.