A battery drives an electric motor which raises a 20 kg mass at a steady speed.

Given that 90% of the electrical energy is converted to mechanical energy, we can say that the mechanical energy produced is 90 joules.Using the formula for kinetic energy (K.E= 0.5 x mass x velocity^2), we can find the velocity of the mass to be 3 m/s.From the given equation, P = IV, we can calculate the power to be (5 A) x (130.7 V) = 653.5 watts.Finally, using the formula for power, we can find the emf of the battery to be 130.7 volts.In summary, the emf of the battery is 130.7 volts.
  • #1
apparatus82
2
0
1. A battery drives an electric motor which raises a 20 kg mass at a steady speed of 3m/s vertically upwards. If 90% of the electrical energy supplied is converted to mechanical energy and the current flowing is 5 A, find the emf of the battery.



2. W=QV
p=mv
P=IV
K.E=.5mv^2


3.

K.E= 90 joules
90/.9=100 joules
W=QV
100=5(1.6x10^-19)V
V = 1.25 x10^20 ?


Correct answer: 130.7 V
Any help is highly appreciated.
 
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  • #2
apparatus82 said:
1. A battery drives an electric motor which raises a 20 kg mass at a steady speed of 3m/s vertically upwards. If 90% of the electrical energy supplied is converted to mechanical energy and the current flowing is 5 A, find the emf of the battery.



2. W=QV
p=mv
P=IV
K.E=.5mv^2


3.

K.E= 90 joules
90/.9=100 joules
W=QV
100=5(1.6x10^-19)V
V = 1.25 x10^20 ?


Correct answer: 130.7 V
Any help is highly appreciated.


Scratch that. I got it now!
Work done = Force x distance
Power = Work done/ Time
Therefore, Power = Force x Speed
 

1. How does a battery drive an electric motor?

A battery provides a source of electrical energy, which is then converted into mechanical energy by the electric motor. This conversion is possible because of the interaction between the magnetic field of the motor and the current flowing through it.

2. What is the purpose of the electric motor in this scenario?

The electric motor is responsible for converting electrical energy into mechanical energy, which is used to raise the 20 kg mass at a steady speed. Without the motor, the battery would not be able to power the movement of the mass.

3. How does the electric motor maintain a steady speed while raising the mass?

The electric motor is designed to operate at a specific voltage and current, which determines the speed at which it rotates. As long as the battery provides a steady source of electricity, the motor will maintain a constant speed, resulting in a steady movement of the mass.

4. Is the battery the only source of energy in this scenario?

Yes, in this scenario, the battery is the only source of energy. The electrical energy stored in the battery is used to power the electric motor, which then raises the mass. However, there may be other factors at play, such as friction and air resistance, which may affect the overall energy efficiency of the system.

5. How does the weight of the mass affect the performance of the system?

The weight of the mass will affect the amount of force required to lift it, which in turn, may affect the amount of electrical energy needed from the battery to power the motor. A heavier mass may require a larger battery or a more powerful motor to maintain a steady speed. However, the physics principles behind the system remain the same regardless of the weight of the mass.

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