A ball of mass 0.7 kg strikes the wall at an angle of 90 degrees with speed 72 km/h. Consider that the bounce lasts for 0.1 s and is perfectly elastic. What is the magnitude of the average reaction force from the wall that acts on the ball?
initial speed: v = 72 km/h = 20 m/s.
mass: m = 0.7 kg
time of the impact: t = 0.1 s
average force: F
The speed after impact is the same as initial speed, but velocity has got the opposite direction. Therefore, Δv = 2v
Δmomentum = Δp = mΔv = 2mv
from the Newton's 2nd Law:
F = Δp/Δt = 2mv/t
F = 20.720/(0.1) = 280 N
Answer: The magnitue of the average force equals 280 N.
FM
Related Physics A Level answers
All answers ▸A cyclist rides 10km. In the first 5km, they climb a hill, averaging 10km/h. In the second 5km, they descend the hill, averaging 30km/h. What is their average speed over the full 10km?
Using Newton's law of universal gravitation, show that T^2 is proportional to r^3 (where T is the orbital period of a planet around a star, and r is the distance between them).
Describe the photoelectric effect and what it tells us about the properties of light .
In the photoelectric effect, what happens as you increase the frequency of light keeping the same intensity constant?