1. (6 pts.) You need to slide a 70.0 kg desk 8.00 meters along a level hallway.
ID: 1603062 • Letter: 1
Question
1. (6 pts.) You need to slide a 70.0 kg desk 8.00 meters along a level hallway. The desk starts at rest. You apply a constant force F on the desk: 300. N.directed slightly downward at an angle of 25.0 below the horizontal. As the desk slides, the magnitude of the kinetic friction force acting on the desk is a constant 260. N. Find the desk's final horizontal velocity. Solve this problem using woRK and the WORK-ENERGY THEOREM not dynamics & kinematics. (Thought question Inot for credit/: Instead. if you were to use dynamics to find the desk's horizontal acceleration, then kinematics to find the desk's final velocity, should you get the same final answer as when you use the work-energy theorem? You can check and see Show your work completely. desk 8.00 meters. BONUS: (+1 pt.) What is the coefficient of kinetic friction between the desk and floor? Note: This is a little tricky! You do NOT need to show your work for this part.Explanation / Answer
resultant force
F=300cos25-260=11.9 N
from work-energy theorem
(1/2)MV2=Fd
(1/2)*70*V2=11.9*8
V=1.65 m/s
Normal force on the ground
N=70*9.8+300sin25=812.8 N
coefficent of kinetc friction
u=f/N=260/812.5=0.32
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