Calculate the magnitude of the change in momentum in each of the following examples.
A 1,200 kg car accelerates from rest to a speed of 20 m/s.
A 75 g pellet moving at 18.0 m/s hits a tree and lodges in it.
A 250 g rubber ball hits the floor at 10.0 m/s and rebounds at 6.0 m/s.
A 60 kg student jogging at 3.0 m/s speeds up to 6.5 m/s.
To calculate the magnitude of the change in momentum in each example, we need to use the equation:
Change in momentum = mass × change in velocity.
1. For the 1,200 kg car accelerating from rest to a speed of 20 m/s:
Change in momentum = 1,200 kg × (20 m/s - 0 m/s)
Change in momentum = 1,200 kg × 20 m/s
Change in momentum = 24,000 kg·m/s
2. For the 75 g pellet hitting a tree and lodging in it:
Change in momentum = (0.075 kg) × (0 m/s - 18.0 m/s)
Change in momentum = (0.075 kg) × (-18.0 m/s)
Change in momentum = -1.35 kg·m/s (negative sign indicates a change in direction)
3. For the 250 g rubber ball hitting the floor at 10.0 m/s and rebounding at 6.0 m/s:
Change in momentum = (0.250 kg) × (6.0 m/s - 10.0 m/s)
Change in momentum = (0.250 kg) × (-4.0 m/s)
Change in momentum = -1.00 kg·m/s (negative sign indicates a change in direction)
4. For the 60 kg student jogging at 3.0 m/s to speeding up to 6.5 m/s:
Change in momentum = (60 kg) × (6.5 m/s - 3.0 m/s)
Change in momentum = (60 kg) × (3.5 m/s)
Change in momentum = 210 kg·m/s
To calculate the magnitude of the change in momentum, we can use the formula:
Δp = m * Δv
where Δp is the magnitude of the change in momentum, m is the mass, and Δv is the change in velocity.
Let's calculate the magnitude of the change in momentum for each example:
1. A 1,200 kg car accelerating from rest to a speed of 20 m/s:
Δp = m * Δv
= 1,200 kg * (20 m/s - 0 m/s)
= 24,000 kg·m/s
Therefore, the magnitude of the change in momentum is 24,000 kg·m/s.
2. A 75 g pellet moving at 18.0 m/s hits a tree and lodges in it:
Δp = m * Δv
= 0.075 kg * (0 m/s - 18.0 m/s)
= -1.35 kg·m/s
Because the pellet lodges in the tree and changes direction, the change in velocity is negative. Therefore, the magnitude of the change in momentum is 1.35 kg·m/s.
3. A 250 g rubber ball hitting the floor at 10.0 m/s and rebounding at 6.0 m/s:
Δp = m * Δv
= 0.250 kg * (6.0 m/s - 10.0 m/s)
= -1 kg·m/s
Similarly to the previous example, the ball changes direction upon rebounding, so the change in velocity is negative. The magnitude of the change in momentum is 1 kg·m/s.
4. A 60 kg student jogging at 3.0 m/s speeds up to 6.5 m/s:
Δp = m * Δv
= 60 kg * (6.5 m/s - 3.0 m/s)
= 210 kg·m/s
In this case, the change in velocity is positive as the student speeds up. Therefore, the magnitude of the change in momentum is 210 kg·m/s.
chanMome=mass(changevelocity)
you can do the math. On the rubber ball, the change in velocity is 16m/s..think that out.