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enot [183]
3 years ago
14

The electric motor has an input energy of 50,000 joules each second. The motor transfers 35,000 joules of useful energy each sec

ond. Calculate the efficiency of the electric motor (show workig out too)
Physics
1 answer:
Sergio039 [100]3 years ago
6 0
W(out)/w(in)
35,000J/50,00J=.7
.7 *100%=70 % efficient
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A soccer ball with a mass of 0.45 kg is kicked and is moving at 8.9 m/s. Find the kinetic
strojnjashka [21]

Answer:

17.82J

Explanation:

Kinetic energy = 1/2 mv^2

Given

Mass M = 0.45kg

Velocity v = 8.9m/s

Therefore,

K.E. = 1/2 x 0.45 x (8.9)^2

= 1/2 x 0.45 x (8.9 x 8.9)

= 1/2 x 0.45 x 79.21

Multiply through

= 35.6445/2

= 17.82J

The kinetic energy of the ball is 17.82J

3 0
3 years ago
What is an example of a form of friction that impedes motion
Travka [436]

Answer:

to me I think is static

Explanation:

that is my own thinking

4 0
3 years ago
A can of sardines is made to move along an x axis from x = 0.47 m to x = 1.20 m by a force with a magnitude given by F = exp(–8x
sattari [20]
If the force were constant or increasing, we could guess that the speed of the sardines is increasing. Since the force is decreasing but staying in contact with the can, we know that the can is slowing down, so there must be friction involved.
Work is the integral of (force x distance) over the distance, which is just the area under the distance/force graph.
The integral of exp(-8x) dx that we need is (-1/8)exp(-8x) evaluated from 0.47 to 1.20 .

I get 0.00291 of a Joule ... seems like a very suspicious solution, but for an exponential integral at a cost of 5 measly points, what can you expect. On the other hand, it's not really too unreasonable. The force is only 0.023 Newton at the beginning, and 0.000067 newton at the end, and the distance is only about 0.7 meter, so there certainly isn't a lot of work going on. The main question we're left with after all of this is: Why sardines ? ?
6 0
3 years ago
A runaway railroad car, with mass 30x10^4 kg, coasts across a level track at 2.0 m/s when it collides with a spring loaded bumpe
Natalija [7]

Answer:

0.775 m

Explanation:

As the car collides with the bumper, all the kinetic energy of the car (K) is converted into elastic potential energy of the bumper (U):

U=K\\frac{1}{2}kx^2 = \frac{1}{2}mv^2

where we have

k=2\cdot 10^6 N/m is the spring constant of the bumper

x is the maximum compression of the bumper

m=30\cdot 10^4 kg is the mass of the car

v=2.0 m/s is the speed of the car

Solving for x, we find the maximum compression of the spring:

x=\sqrt{\frac{mv^2}{k}}=\sqrt{\frac{(30\cdot 10^4 kg)(2.0 m/s)^2}{2\cdot 10^6 N/m}}=0.775 m

8 0
3 years ago
Read 2 more answers
Can someone give me an example or explanation of calculating energy from voltage? Many thanks!
antoniya [11.8K]
Expression to calculate energy from voltage: E= V*Q where E= energy, V= voltage, and Q= charge

Additional help:
-To find the Voltage ( V )
[ V = I x R ] V (volts) = I (amps) x R (Ω)

-To find the Current ( I )
[ I = V ÷ R ] I (amps) = V (volts) ÷ R (Ω)

-To find the Resistance ( R )
[ R = V ÷ I ] R (Ω) = V (volts) ÷ I (amps)

I hope that helps to some extent-
7 0
3 years ago
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