# physics

posted by .

img145.imageshack.us/img145/7130/picture1n.png

this is basically the diagram to my question

A person of mass m = 62 kg is doing push-ups as shown in the attached figure. The distances are a = 91 cm and b = 60% of l1. Calculate the vertical component of the normal force exerted by the floor on both hands.

Can someone please explain this problem to me i don't know how to approach it..i understand that i will have to use times each distance by the weight but i don't understand what to do next?

• physics -

I cant load the site, I will try later. The idea is that you sum moments (clockwise+, counterclockwise-) and set equal to zero. A moment is Force*distance*sinAnglebetweenthem(usually 90 degrees).

• physics -

y-direction: N1 + N2 - Fg = 0
x-direction: L1 x N1 - L2 x N2 = 0

Fg = mg

• physics -

you just have to add w w w to the website

• physics -

can u explain to me what you mean by y direction is equal to and for the force *distance *the angle i don't know the angle for the question

• physics -

Since we're only trying to find the Normal Force exerted by the two hands, we automatically assume that it's in mechanical equilibrium, thus equaling to zero.

• physics -

okay but can you explain to me how to find N1 and N2

• Anonymous and bobpursley -

can you please Anonymous and bobpursley explain this to me.

• physics -

isolate N1 for the first eq:
N1 = Fg - N2

eq 2:
N1 x L1 - N2 x L2 = 0
sub N1 from eq 1 to eq 2.

(Fg - N2)L2 - N2 x L2=0
(Fg - N2 x L2) - N2 x L2 = 0
Fg = N2 x L2 + N2 x L1
Fg = N2(L2+L1)

since we already know Fg = mg, we isolate for N2

N2 = Fg/(L2+L1)

Thus the normal for N2 is found. Now look back to eq 1 again:
N1 + N2 - Fg = 0
then isolate for N1 by substituting the found value N2.

Make sure you convert cm to m.

• physics -

Once the N1 is found, add the to Normal forces and voila!

## Similar Questions

1. ### Physics

A block with a mass of 5.0 kg is held in equilibrium on an incline of an angle with a measure of 30.0 degrees by the horizontal force F. Find the magnitude of F. Find the normal force exerted by the inbline on the block. (disregard …
2. ### AP Physics - Equilibrium

The Achilles tendon is attached to the rear of the foot as shown in the figure below. When a person elevates himself just barely off the floor on the ball of one foot, estimate the tension Ft in the Achilles tendon (pulling upward) …
3. ### AP Physics - Static Equilibrium

A man doing push-ups pauses in the position shown in the figure. His mass is 75-kg. 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 …
4. ### calculus

Hi, I have online homework for calculus and I have to input two equations that will describe this graph. I have an image but Jiskha won't let me link to any websites... if this is allowed the URL to the image of the graph is img145.imageshack.us/ …
5. ### physics

A man doing push-ups 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 …
6. ### Physics

A man doing push-ups 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 …
7. ### Budget project - Anonymous

http://www.jiskha.com/display.cgi?id=1300146111 = Your earlier post http://img145.imageshack.us/f/60103724.jpg/ #1 - March's wages should be \$2000.00 and the savings for March should be \$1200.00 (as you have it). #2 - The total for
8. ### phyics

The figure shows a person whose weight is W = 500 N doing push-ups. Find the normal force exerted by the floor on (a) each hand and (b) each foot, assuming that the person holds this position.
9. ### physics

The figure shows a person whose weight is W = 670 N doing push-ups. Find the normal force exerted by the floor on (a) each hand and (b) each foot, assuming that the person holds this position.
10. ### math

Ali is planning to keep fit through practicing push-ups for 21 days. on the first day, he can only do 14 push-ups in a minute. He plans to do x more push-ups in a minute on the next day. How many push-ups can he do in a minute on 11th …

More Similar Questions