AP Physics  Static Equilibrium
posted by Phillip .
A man doing pushups pauses in the position shown in the figure. His mass is 75kg. Determine the normal force exerted by the floor on each hand and on each foot.
img145.imageshack.us/img145/7130/picture1n.png
(copy into url bar)
a = 40 cm
b = 95 cm
c = 30 cm
W = mg = 735 N
I can't figure out how to find the amount of force being exerted at the hands/feet if you don't know the mass at each location. Help would be very much appreciated.

AP Physics  Static Equilibrium 
drwls
Assume the forces on each foot are equal, and the forces on each hand are equal. The total on all four appendages must equal 735 N.
Set the total moment about a line through the feet/floor contact points equal to zero. This will let you solve for the sum of the forces on the hands. You will need to know where the center of mass of the body is. This is shown as "b" in your figure 
AP Physics  Static Equilibrium 
Phillip
I thought W was the center of mass?
Also, are you saying to use moment of inertia I to solve, and if so, how would I set up the equations? I'm not good at equilibrium problems. 
AP Physics  Static Equilibrium 
drwls
W is the center of mass. The moment of inertia does not play a role in statics problems.

AP Physics  Static Equilibrium 
Phillip
I still don't know get to set up how to solve for the forces of the hands/feet if you don't know their distinct masses and only have the center of mass...

AP Physics  Static Equilibrium 
drwls
You don't need to know the distinct masses of hands and feet... just the total mass and that it acts as if it were at the Center of Mass.
The height of the CM above the floor, although shown in the figure, will not matter in this problem.
Respond to this Question
Similar Questions

Physics
The drawing shows a person (weight W = 592 N, L1 = 0.841 m, L2 = 0.410 m) doing pushups. Find the normal force exerted by the floor on each hand and each foot, assuming that the person holds this position. force on each hand N force … 
Physics
The drawing shows a person (weight W = 592 N, L1 = 0.841 m, L2 = 0.410 m) doing pushups. Find the normal force exerted by the floor on each hand and each foot, assuming that the person holds this position. force on each hand N force … 
PHYSICS HELP!
A man doing pushups pauses. His mass is 80kg. Determine the normal force exerted by the floor on each hand and on each foot. a = 40 cm b = 95 cm c = 30 cm W = mg = 784 N 
PHYSICS HELP!
A man doing pushups pauses. His mass is 80kg. Determine the normal force exerted by the floor on each hand and on each foot. a = 40 cm b = 95 cm c = 30 cm W = mg = 784 N 
physics
A man doing pushups pauses in the position shown in the figure . His mass m = 80 kg. In push up position: From hands to waist = 40 cm From waist to feet = 95 cm height  heel of foot to ground = 30 cm Determine the normal force exerted … 
physics
img145.imageshack.us/img145/7130/picture1n.png this is basically the diagram to my question A person of mass m = 62 kg is doing pushups as shown in the attached figure. The distances are a = 91 cm and b = 60% of l1. Calculate the … 
Physics
A man doing pushups pauses in the position shown in the figure . His mass = 68 kg. Determine the normal force exerted by the floor on each hand. Determine the normal force exerted by the floor on each foot. 
Physics
A man doing pushups pauses in the position shown in the figure . His mass = 68 kg. Image: img145.imageshack.us/img145/7130/picture1n.png a= 40 cm b= 95 cm c= 30 cm Determine the normal force exerted by the floor on each hand. Determine … 
physics
The drawing shows a person (weight W = 581 N, L1 = 0.843 m, L2 = 0.404 m) doing pushups. Find the normal force exerted by the floor on each hand and each foot, assuming that the person holds this position. force on each hand N force … 
physics
The figure shows a person whose weight is W = 670 N doing pushups. Find the normal force exerted by the floor on (a) each hand and (b) each foot, assuming that the person holds this position.