Not sure where to start? These are the lessons and games we recommend most to students, parents and teachers on Basic-mathematics.com. Each lesson explains the topic in plain language, walks you through worked examples step by step, and ends with practice so you can check your understanding. Pick one below, or use the menu to find lessons on fractions, algebra, geometry, statistics and more.
These impulse momentum theorem problems will help you clearly see how to
apply the impulse-momentum theorem. Study the solution we give
carefully so you can tackle other similar problems.
Earlier in impulse and momentum, we saw that Ft = ▲mv
In many situations, the mass will not change. In this case, we can also rewrite the formula as Ft = m▲v or Ft = m(final speed - initial speed)
Problem #1:
What average force is required to push a 20-kg stroller with your toddler in it for 5 seconds if the weight of the toddler is 15 kg? Suppose that you can push with a speed of 1 m/s and the stroller is initially at rest.
Solution:
You are pushing a total mass of 20 kg + 15 kg = 35 kg
Ft = m(final speed - initial speed)
F × 5 = 35 kg × (1 m/s - 0)
F × 5 = 35
Since 7 × 5 = 35, F = 7 newtons.
Problem #2:
An average force of 50 N is exerted on a 4-kg cart for 2 seconds.
a. What is the impulse?
b. What is the change in momentum?
c. What is the mass's change in velocity?
Solution:
a. Impulse = F × t
Impulse = 50 N × 2
Impulse = 100 N.s
b.
Impulse = change in momentum
So, change in momentum = impulse = 100 N.s
c.
The mass's change in velocity is ▲v
F × t = m▲v
100 N.s = 4 × ▲v
Since 100 = 4 × 25, ▲v = 25 m/s
Problem #3:
A soccer ball is heading toward a wall with a speed of 20 meters per second. After hitting the wall, the ball bounces back with a speed of 25 meters per second. The ball was in contact with the wall for 0.003 second. What is the average force the wall exerted on the ball?
Solution:
F × t = m(final speed - initial speed)
The final speed is 25 meters per second
The initial speed is -20 meters per second. This speed is negative because the ball is going to the other direction.
The mass of a soccer ball is 0.45 kg
F × 0.003 = 0.45 (25 - -20)
F × 0.003 = 0.45 (45)
F × 0.003 = 20.25
F = 20.25 / 0.003
F = 6750 N
Share this page