Mapoob Sapling Learning Nate the Skate was an avid physics student whose main no
ID: 1581704 • Letter: M
Question
Mapoob Sapling Learning Nate the Skate was an avid physics student whose main non-physics interest in life was high-speed skateboarding. In particular, Nate would often don a protective suit of Bounce-Tex, which he invented, and after working up a high speed on his skateboard, would collide with some object. In this way, he got a gut feel for the physical properties of collisions and succeeded in combining his two passions. On one occasion, the Skate, with a mass of 131 kg, including his armor, hurled himself against a 813-kg stationary statue of Isaac Newton in a perfectly elastic linear collision. As a result, Isaac started moving at 1.61 m/s and Nate bounced backward. What were Nate's speeds immediately before and after the collision? (Enter positive numbers.) Ignore friction with the ground. Before Number m/s After Number m/sExplanation / Answer
Conserving momentum,
m1*u = m1*v1 + m2*v2
here : m1 = 131 kg
m2 = 813 kg
u = initial speed of Nate
v1 = final speed of Nate
v2 = 1.61 m/s
So, 131*u = 131*v1 + 813*1.61 ------------ (1)
Now, conserving energy (as the collision is perfectly elastic ) :
0.5*131*u^2 = 0.5*131*v1^2 + 0.5*813*1.61^2 ----------- (2)
Solving the above two equations , we get :
u = 5.8 m/s <--------- answer
v1 = - 4.2 m/s <---------- answer