A(n) 840-kg dragster accelerates on a race track from rest to 85 km/h in 0.90 seconds.
(a) What is the change in momentum of the dragster?
(b) What is the average force exerted on the dragster?
(c) What exerts that force?
(a) Multiply m by the change in V. Convert the final speed to m/s first.
(b) Average force = (momentum change)/time
(c) The track exerts the force against the tires.
a) If you did not know before, momentum is equal to mass times velocity, p=mv.
The others, "drwls", has explained it well enough for you.
To find the change in momentum of the dragster, we can use the formula:
change in momentum = mass * change in velocity
(a) First, let's convert the final velocity from km/h to m/s:
85 km/h = 85,000 m/3600 s = 23.6 m/s
Now we can calculate the change in momentum:
change in momentum = 840 kg * (23.6 m/s - 0 m/s)
change in momentum = 840 kg * 23.6 m/s
change in momentum ≈ 19,824 kg·m/s
Therefore, the change in momentum of the dragster is approximately 19,824 kg·m/s.
(b) To find the average force exerted on the dragster, we can use the formula:
average force = change in momentum / change in time
The change in time is given as 0.90 seconds.
average force = 19,824 kg·m/s / 0.90 s
average force ≈ 22,026 N
Therefore, the average force exerted on the dragster is approximately 22,026 N.
(c) The force exerted on the dragster is exerted by the race track.
To find the change in momentum of an object, you can use the formula:
Change in momentum = mass × change in velocity
Given values:
Mass of the dragster (m) = 840 kg
Initial velocity (u) = 0
Final velocity (v) = 85 km/h = 85 × (1000/3600) m/s = 23.61 m/s
Change in time (Δt) = 0.90 s
(a) Now, let's calculate the change in momentum of the dragster:
Change in momentum = mass × change in velocity
Change in momentum = 840 kg × (23.61 m/s - 0 m/s)
Change in momentum = 840 kg × 23.61 m/s
To find the value, multiply the mass of the dragster by the change in velocity.
(b) The average force exerted on the dragster can be found using the impulse-momentum equation:
Force × time = Change in momentum
Rearranging the equation, we get:
Force = Change in momentum / time
Force = (840 kg × 23.61 m/s) / 0.90 s
To find the average force, divide the change in momentum by the change in time.
(c) The force exerted on the dragster is exerted by the track. As the dragster accelerates, the tires of the dragster push against the track, exerting a force in the forward direction.
In summary:
(a) The change in momentum of the dragster is calculated by multiplying the mass of the dragster by the change in velocity.
(b) The average force exerted on the dragster is found by dividing the change in momentum by the change in time.
(c) The force is exerted by the track, as the tires push against the track to propel the dragster forward.