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 123 kg, including his armor, hurled himself against a 899 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: m/s after: m/s *by the way, this brief bio of nate the skate is written in the past tense, because not long ago he forgot to put on his bounce-tex before colliding with the washington monument in a perfectly inelastic collision.

Explanation:

In the elastic collision , law of conservation of momentum will be followed.

Initial total momentum of the system

= 123 u + 0 = 123u ( u is initial velocity of nate)

Final momentum of the system

= 899 x 1.61 + 123 v

= 1447.39 + 123 v

For conservation of momentum

123u = 1447.39 + 123 v

For perfectly elastic collision

relative velocity of approach = relative velocity of separation

u - 0 = 1.61 - v

Putting this value of u in the previous equation

123 ( 1.61 -v ) = 1447.39 +123v

198.03 - 123v = 1447.39 +123v

- 1249.36 = 246 v

v =  - 5.078 m /s

u = 1.61 + 5.078

= 6.688 m /s

the bal will not change its velocity.

air exerts forces on falling objects near earth’s surface.

explanation:

the term 'free falls' refer to object that are falling towards the earth, in a situation in which gravity is the only force acting on the object.

for an object in free fall, the acceleration is constant (g, the gravitational acceleration), and so the velocity of the object constantly increases.

for objects near earth's surface, there is always another force acting on the object: the resistance due to the air. this force is opposed to the direction of fall of the object, and it is proportional to the velocity of the object, so as the object falls down, this force increases up to a point when it balances the force of gravity, and the object continues its motion at constant velocity (called terminal velocity). since in this case gravity is not the only force acting on the object, we are not in a situation of free fall.