Show all work. Must include full model- all 3 kinematic graphs, pictoral diagram
ID: 1418266 • Letter: S
Question
Show all work. Must include full model- all 3 kinematic graphs, pictoral diagram, and motion maps
Only fully supported answers will receive full credit.
( It should be apparent that there is not enough space provided below questions to work on this sheet , please use additional paper)
1. A person wants to get his keys to a friend on the third floor of a building. The stairs
and elevator are out in the building so the only way to get the keys to the friend is to
throw them straight upward. The keys are thrown with a velocity of 19 m/s so that
they reach the third floor traveling at 1 m/s. How high is the third floor?
2. A tailback initially running at a velocity of 5.0 m/s becomes very tired
and slows down at a uniform rate of 0.25 m/s^2. How fast will he be
running after going an additional 10 meters?
3. A 0.50 kg can of beans rolled off the top shelf in my pantry at a speed of 0.10 m/s. The top shelf is 2.50 m high. Find the velocity of the can of beans just before it hits the ground. (magnitude and direction)
4. 3. An elevator is moving downward at 4.0 m/s when someone pushes the emergency stop button. It travels a further 2.9m before coming to rest.
Explanation / Answer
(1)
Let the height of 3rd floor be h.
vi = 19 m/s
vf = 1 m/s
a = - 9.8 m/s^2
vf^2 = vi^2 + 2*a*h
1 = 19^2 - 2*9.8*h
h = 18.36 m
(2)
vi = 5.0 m/s
a = - 0.25 m/s^2
s = 10 m
vf^2 = vi^2 - 2*a*s
vf^2 = 5.0^2 - 2*0.25*10
vf = 4.47 m/s
Speed after going an additional 10 meters, vf = 4.47 m/s
(3)
Using Energy Conservation,
Initial Potential Energy + Initial Kinetic Energy = Final Kinetic Energy
m*g*h + 1/2*m*vi^2 = 1/2*m*v^2
9.8*2.5 + 1/2*0.1^2 = 1/2*v^2
v = 7.0 m/s
(4) Incomplete question !!