Physics B Help!!!

Test Preparation AP Test Preparation
1

<p>This is the question:</p>

<p>The operating efficiency of a .5 A, 120 V electric motor that lifts a 9 kg mass against gravit at an average velocity of .5m/s is most nearly:</p>

<p>a. 7%
b. 13%
c. 25%
d. 53%
e. 75%</p>

<p>how do i do this? thanks.</p>

2

<p>Where ideal power output is P = IV
This motor is working @ P=Fv</p>

<p>Therefore Fv/IV = 45/60 = 0.75
E</p>

3

<p>how u get 45?</p>

4

<p>mgv</p>

<p>9kg x 0.5m/s x 10m/s^2</p>

5

<p>mech power = F X V = 9 X 10 X .5 = 45.</p>