Two balls, A and B, each having a mass of 1.0 kg, are dropped from a height of 1
ID: 1865025 • Letter: T
Question
Two balls, A and B, each having a mass of 1.0 kg, are dropped from a height of 1.0 m above the floor. Ball A bounces, rebounding to a height of 0.70 m, while Ball B does not bounce, and comes to rest on the floor.
A) Determine the speed of ball A just before impact.
B) Determine the speed of ball B just before impact.
C) Determine the speed of ball A just after leaving the floor (traveling upward).
D) If both collisions lasted for the same time interval, was the average force exerted by the floor on ball A greater than, less than, or equal to the average force exerted by the floor on ball B?
E) Explain your reasoning to part D
F) During the collision, dis ball A lost more, less, or the same amount of kinetic energy as ball B?
G) Explain your reasoning to part F.
Explanation / Answer
(A) Using the formula , V = Square root( 2gh) = square root (2 x 9.8 x 1 ) = 4.43 m/s
(B) Same as (A) i.e. 4.43 m/s
(C) Similar to (A), V = Square root( 2gh) = square root (2 x 9.8 x 0.7 ) = 3.70 m/s
(D) Average Force exerted by Floor to A is greater than A
(E) As per Newtons' Second Law, Force is proportional to Change in momentum
Change in momentum of A = 1 x ( 3.7 + 4.43 ) = 8.13 Kg m/s
while Change in momentum of B = 1 x 4.43 = 4.43 Kg m/s
Therefore since Change in momentum of A is greater, hence Force on A is also greater.
(F) Ball A lose less Energy
(G) Ball A still has speed of 3.37 m/s, while Ball B has Zero speed after collision