Work & Power of Pulley System Homework

Click For Summary
SUMMARY

The discussion centers on calculating the work done and power delivered in a pulley system involving a 20 kg box raised by a 25 N force. The work done on the crate is determined using the equation W = Fd, resulting in 147.15 J. To find power, participants discuss using the formula P = Fv, emphasizing the need to calculate the correct velocity and time based on acceleration derived from F = ma. The relationship between work, power, and potential energy change is also highlighted.

PREREQUISITES
  • Understanding of Newton's Second Law (F = ma)
  • Familiarity with work-energy principles (W = Fd)
  • Knowledge of power calculations (P = Fv)
  • Basic kinematics for deriving time from displacement and acceleration
NEXT STEPS
  • Study the relationship between work and potential energy in mechanical systems
  • Learn how to derive velocity from acceleration and displacement using kinematic equations
  • Explore the implications of massless pulleys in mechanical advantage calculations
  • Investigate real-world applications of power calculations in pulley systems
USEFUL FOR

Students studying physics, particularly those focusing on mechanics, engineers designing pulley systems, and anyone interested in the practical applications of work and power in mechanical systems.

nathan8
Messages
8
Reaction score
0

Homework Statement



20 Kg box is raised 0.75m by a constant 25N force applied at the end of the cord if the pulleys are massless, determine work done on the crate. What is the power delivered at the end of the cord at this point?

Identical pulley system
http://www.oldschool.com.sg/modpub/20204469354a2bdb19c0115


Homework Equations



W=Fd I found that W=20(9.81)*0.75 = 147.15 J

P=Fv

The Attempt at a Solution



I am having trouble with the power portion, I am not sure how to find the correct velocity to apply also confused as to which force the 25N or the 20(9.81)

Thanks
 
Last edited by a moderator:
Physics news on Phys.org
Power is work divided by time, for the time consider that you can find acceleration from F = ma and since you know the total displacement the time can be derived from a kinematics equation.
 
Would Power = F*v work here?

Then just find the velocity with 2Va = -Vb

And use the 25N force times this velocity?

Am I on the right track with the work done on the crate, being the change in potential energy?
 

Similar threads

Find the velocity and acceleration of a pulley in a mass-spring system
  • · Replies 14 ·
Replies
14
Views
2K
Experimental Design: Pulley and Mass Hangers
  • · Replies 30 ·
2
Replies
30
Views
4K
Avg Power in a Rotational Energy/Work Problem
  • · Replies 6 ·
Replies
6
Views
2K
Atwood with Sliding mass and real pulley
  • · Replies 4 ·
Replies
4
Views
4K
Block-pulley system and kinetic energy
  • · Replies 1 ·
Replies
1
Views
3K
Force applied on the pulley of a system
  • · Replies 8 ·
Replies
8
Views
3K
Work Done on Pulley System: 840J
  • · Replies 7 ·
Replies
7
Views
2K
How Much Work is Done Raising a Load with a Two-Pulley System?
  • · Replies 2 ·
Replies
2
Views
2K
Acceleration and Tension in a Pulley System
  • · Replies 9 ·
Replies
9
Views
6K
Worker Sim Pulma Sheen: Solving a Pulley Problem
  • · Replies 6 ·
Replies
6
Views
2K