
Physics Physics Forum 
 LinkBack  Thread Tools  Display Modes 
November 12th, 2010, 12:34 AM  #1 
Senior Member Joined: Oct 2009 Posts: 893 Thanks: 1  A shopper in a supermarket pushes a cart with a force
[color=#0040FF]1 ) A shpooer in a supermarket pushes a cart with a force of 25 N directed at an angle of 18 downward from the horizontal . Find the work done by the shopper as she moves a 40 m lenght of the aisle ?[/color] W = (35 N)(40) cos 25o W = (35 N)(40.906) W = 1 586 Nm = W = F d cos 25 = 1 586 J [color=#0040FF]2 ) Tarzan swing on a 25 m long vine initially inclined at angle of 32 with the vertical . What is the speed at the bottom of the swings a) if he start from rest ? b) if he pusches off with speed of 5.00 m/s ?[/color] a ) if he start from rest ? = zero 
November 12th, 2010, 06:03 AM  #2 
Senior Member Joined: Jul 2010 From: St. Augustine, FL., U.S.A.'s oldest city Posts: 12,131 Thanks: 432 Math Focus: Calculus/ODEs  Re: A shopper in a supermarket pushes a cart with a force
1.) First, we need to find the horizontal component of the shopper's pushing force. This is given by: where is the angle of inclination. For a constant force along a line, we know: The work W done by an agent exerting a constant force is the product of the component of the force in the direction of the displacement and the magnitude of the displacement of the force. Thus, in this situation, we have: 2. By applying the principle of constancy of mechanical energy, we can derive a formula to answer both parts of the question. The sum of the initial kinetic and potential energies will equal the sum of the final kinetic and potential energies. If we measure the ycoordinates from the center of rotation (which we take as the origin), then: Therefore: Using the constancy of energy, we have Multiply through by : Solve for : Now, all you need to do is plug in the known and given data: for (a) and for (b) 

Tags 
cart, force, pushes, shopper, supermarket 
Thread Tools  
Display Modes  

Similar Threads  
Thread  Thread Starter  Forum  Replies  Last Post 
Is there a formula to know the angle of an object, on a Cart  dolphonebublein  Linear Algebra  1  December 26th, 2012 01:55 PM 
for a golf cart motor. They're about 1.5hp 36 volts DC.  rsoy  Physics  0  June 15th, 2012 04:21 AM 
Supermarket card collection  Davdof  Advanced Statistics  4  June 12th, 2011 11:40 AM 
Force  MATHS  Physics  2  January 17th, 2009 01:50 PM 