A chair of mass 12kg is pushed along a level floor by a force that is at an angle of θ=35.0degrees below the horizontal. The coefficient of friction between the chair and the floor is µ=0.430. The power that the force provides to move the chair in a straight line at a constant speed of 3.8m/s is?
2007-05-06 16:01:51 · 3 answers · asked by ♡♥EM♡♥ 4 in Science & Mathematics ➔ Physics
the correct answer is 275W, but i'm not sure how they get it.
2007-05-06 16:39:03 · update #1
Let the applied force be P at 35 degree below the horizontal.
Then its component Psin35 acts vertically downward.
And component Pcos35 acts horizontally to move the chair
P cos35 balances Friction force to move the chair with constant velocity
Normal reaction on chair N =weight W of chair + Psin35
Friction force = co eff. of friction*normal reaction N
Friction force=0.430*(12*9.8 + Psin35 )
Pcos 35 =Friction force=0.430*(12*9.8 + Psin35 )
Pcos 35 -0.430*Psin35 =0.430 *12*9.8
P[0.819 -0.43*0.573[ = 50.568
P *0.572 =59.568
P = 50.568 / 0.572 = 88.4 newton
Power = force(P). velocity v=Pv cos 35=335.9*cos35
Power = 275 watt
2007-05-06 17:21:08 · answer #1 · answered by ukmudgal 6 · 0⤊ 2⤋
0.43*12*9.81*3.8 = 192.35 watts
2007-05-06 23:15:14 · answer #2 · answered by Helmut 7 · 0⤊ 0⤋
125AMP
2007-05-06 23:10:50 · answer #3 · answered by johny v 1 · 0⤊ 1⤋