Calculating Speed of Mass Given Constant Power & Force

Click For Summary

Homework Help Overview

The discussion revolves around calculating the speed of an 8.00-kg mass subjected to a constant power of 45.0 W and an initial force of 5.00 N. The mass is initially moving in the direction of the force, and the problem involves understanding the relationship between power, force, and velocity over a time period of 4.00 seconds.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • Participants explore the concept of power and its units, questioning how power relates to force and velocity. There is an attempt to clarify the role of integration in the problem, with some participants expressing uncertainty about their mathematical skills. Others discuss the implications of the force being constant only at the initial moment.

Discussion Status

The discussion is active, with participants providing insights into the relationship between power and force. Some guidance has been offered regarding the understanding of power as a rate of energy transfer, and there is an ongoing exploration of how energy changes over time. Multiple interpretations of the problem are being considered, particularly regarding the changing force.

Contextual Notes

Participants note that the force is not constant throughout the duration of the problem, which may affect the calculations. There is also a mention of the need for additional information to fully resolve the problem.

Fluent
Messages
7
Reaction score
0
A constant direction force delivers a constant power of 45.0 W to an 8.00-kg mass which is
initially moving in the direction of the force. At t = 0 s, the force is 5.00 N.
Calculate the speed of the mass after 4.00 s.

I've tried to do several different things, however I believe you need to integrate. My intregration skills are really weak, so please don't assume I'll know what you're doing if you skip a lot of steps.

Thanks.
 
Physics news on Phys.org
Welcome to PF.

You're in luck. You won't need to integrate.

But you will need to understand what power is.

Like what units is power expressed in?
 
Kg m^2/s^3

Few more points would be helpful.

Thanks
 
OK and how is power related to Force?

Power = Force times ...?
 
velocity.. however unfortunately the answer is not 9 m/s. The other information is needed to solve this.. as the force isn't the same throughout.. (it's 5.00 N only at t = 0 s)
 
You are jumping ahead a bit.

The 9 m/s is the speed at t=0 however.

Now think about what is a watt? A Joule/sec perhaps?

And how many seconds? So how many Joules were added to the energy of the mass? ...

And how many joules of energy did the mass have at t=0? And added together as Kinetic energy how fast does that mean the mass is going?
 
Ahh thanks a lot man.. appreciate it.
 

Similar threads

Work Pulley Problem with constant speed
  • · Replies 2 ·
Replies
2
Views
1K
Why can we move the spring with constant speed when we apply a force?
  • · Replies 29 ·
Replies
29
Views
3K
Distribution of Energy when work is done on a system of 2 masses connected by a spring
  • · Replies 17 ·
Replies
17
Views
2K
What is the energy conservation principle in a two masses and pulley problem?
  • · Replies 33 ·
2
Replies
33
Views
4K
Finding power without given speed or time
  • · Replies 2 ·
Replies
2
Views
6K
Calculating the Force of a Jump on the Moon
  • · Replies 10 ·
Replies
10
Views
3K
How Do You Calculate Race Car Acceleration and Power Output?
  • · Replies 20 ·
Replies
20
Views
2K
Speed of train car when sand spilling out from it
  • · Replies 17 ·
Replies
17
Views
4K
What is the relationship between engine power, force, and speed?
  • · Replies 8 ·
Replies
8
Views
4K
Finding the New Acceleration Given Point Charges
  • · Replies 10 ·
Replies
10
Views
6K