Acceleration issue -- A 120W motor starts to lift a load of 20 kg....

In summary, the question asks how much energy is needed to maintain a vertical velocity of 0.5 m/s for a mass of 20 kg with a 120 watt motor.
  • #1
Grindelwald
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Okay, here is a question I just can't solve.

The 120W motor starts to lift a load of 20 kg. During which time, this load will reach a speed of 0.5 m / s, taking into account the potential energy.
PS: Ignore losses in the mechanism!
 
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  • #2
Welcome to PF.
Is this question homework?

You know that potential energy; Ep = m·g·h
How much energy will be used to maintain a vertical velocity of 0.5 m/s ?
Is that more or less than the motor 120 W ?

As the mass starts to move slowly, all 120 W will be available to accelerate the mass.
Ek = ½·m·v²

What is the actual question.
 
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  • #3
Baluncore said:
Welcome to PF.
Is this question homework?

You know that potential energy; Ep = m·g·h
How much energy will be used to maintain a vertical velocity of 0.5 m/s ?
Is that more or less than the motor 120 W ?

As the mass starts to move slowly, all 120 W will be available to accelerate the mass.
Ek = ½·m·v²

What is the actual question.
Thank you for welcoming me.

Yes it is.

Alright, I know formula for potential energy.
Motor power remains the same. 120 W.

Question is how much time is needed to reach the speed of 0.5 m/s by lifting mass of 20 kg with motor 120 W taking in count potential energy. I hope you can understand me because my English knowledge is not that good.
 
  • #4
[Moderator: Moved from a technical forum. No template.]
 
  • #5
This is an energy conservation problem.

The energy ##dE## provided for a constant power ##P## applied during time interval ##dt## is ##dE = Pdt##.

The energy required for a force ##mg## applied during a distance ##dx## is ##dE_p = mgdx##.

The energy required for a force ##ma## applied during a distance ##dx## is ##dE_k = madx##.

Therefore, what you are providing should equal the sum of what is required. ##dt## is what your looking for. What you know is the velocity ##dv## (I'm assuming the initial velocity is 0), not the distance ##dx##. So you have to transform the expression on the 'required' side in terms of ##v##, ##dv##, ##t## and/or ##dt##. Solve the obtained differential equation to find ##\Delta t##.
 
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Likes 2milehi, Lnewqban, Grindelwald and 1 other person

1. What is acceleration?

Acceleration is the rate of change of an object's velocity over time. It is the measure of how quickly an object's speed is increasing or decreasing.

2. How is acceleration calculated?

Acceleration can be calculated by dividing the change in velocity by the change in time. The formula for acceleration is a = (vf - vi) / t, where vf is the final velocity, vi is the initial velocity, and t is the time interval.

3. What is the relationship between acceleration and force?

According to Newton's second law of motion, the acceleration of an object is directly proportional to the net force acting on the object and inversely proportional to its mass. This means that the greater the force applied to an object, the greater its acceleration will be.

4. How does the mass of the load affect the acceleration of the motor?

The mass of the load has a direct impact on the acceleration of the motor. The greater the mass of the load, the more force the motor needs to exert in order to accelerate it. This means that the acceleration will be slower for a heavier load compared to a lighter load.

5. What other factors can affect the acceleration of the motor?

Other factors that can affect the acceleration of the motor include the power of the motor, the friction between the motor and the load, and the efficiency of the motor. These factors can impact the amount of force the motor is able to generate and therefore affect its acceleration capabilities.

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