# Physics

posted by .

A person holds an object of mass m = 4.2 kg on the palm of the hand with the arm stretched. Use the torque equilibrium equation to determine the magnitude of the force F exerted by the biceps muscle when a = 25 cm, b = (0.15 · a), and the angle θ = 75°. Neglect the weight of the lower arm

• Physics -

(a+b)(Fg)-b(Fcosθ) = 0
-->solve for F

Have you done #1 or #3 of the assignment? If you have, please help!

• Physics -

No but I am going crazy trying to do the calculations! Grr...wish I had more time to review before doing this h/w!

Thanks though. If I figure it out i'll post back here, ok

• Physics -

Hey Anna, can you break that down. I'm so confused!

• Physics -

Fg in the eqn she gave is mg...

• Physics -

Did any of you guys find 1 or 3?

• Physics -

So, basically i wrote down the torque equilibrium equation where torque equals 0 and the point of reference being the one shown in the diagram. The distance from the point of reference to where Fg is applied is a PLUS b since a is just the distance from the point where F is applied...NOT from the point of reference. The signs you can find using the right-hand rule..i used positive as counterclockwise..so torque is pointing towards you.

• Physics -

Anna if u are having trouble with number 3, have a look at Ex5.2 it will help.

• Physics -

these are the steps to do number 3. i still have yet to try it though:

first you need all the euations of the forces

so horizontal and vertcal

then you need torque

so once you hv your torque youll hv lots of L

you should factor that out

nd solve for T

then sub T into the horizontal forcees equation

nd solve for Rx

And for Question 2 are we supposed to convert cm to m and when we find b, there's no given units so am i supposed to just multiply it with a and it automatically becomes the same unit as a?

• Physics -

the units are given.. it's cm throughout..you don't have to convert because the units for l get canceled out in the end anyways

i got an answer around 3000 for #3? Anyone else get something similar?

• Physics -

yep, it's supposed to be a huge number for #3

• Physics -

i got around 4000s. Hey for question 2 is it supposed to be a tremendous number as well. I got like 4450

• Physics -

Did anyone figured out #1?

• Physics -

No! I've tried multiple ways to do it.. and yet still not getting the right answer. I think I'm messing up my coordiante system and the angles for the forces..

• Physics -

Question #1

T(l1)cos30 + Warm(l2)cos30 - WM(l3)cos30
solve for T

• Physics -

time's up..lol

Thanks guys!

## Respond to this Question

 First Name School Subject Your Answer

## Similar Questions

1. ### Physics

An athlete at the gym holds a 4.33 kg steel ball in his hand. His arm is 75.0 cm long and has a mass of 5.28 kg. What is the magnitude of the torque about his shoulder if he holds his arm straight out to his side, parallel to the floor?
2. ### physics

An athlete at the gym holds a 4.33 kg steel ball in his hand. His arm is 68.7 cm long and has a mass of 4.69 kg. What is the magnitude of the torque about his shoulder if he holds his arm straight out to his side, parallel to the floor?
3. ### physics

An athlete at the gym holds a 4.33 kg steel ball in his hand. His arm is 75.0 cm long and has a mass of 5.28 kg. What is the magnitude of the torque about his shoulder if he holds his arm straight out to his side, parallel to the floor?
4. ### college physics

A cook holds a 1.90 kg carton of milk at arm's length. What force B must be exerted by the biceps muscle?
5. ### physics

hey, i was wondering if someone could explain and help me with this problems. please and thank you! A person holds an object of mass m = 4 kg on the palm of the hand with the arm stretched as shown in the attached figure. Use the torque …
6. ### physics

An athlete at the gym holds a 5.29 kg steel ball in his hand. His arm is 67.0 cm long and has a mass of 4.57 kg. What is the magnitude of the torque about his shoulder if he holds his arm straight out to his side, parallel to the floor?
7. ### physics

A person holds a 1.56 baseball in his hand, a distance of 34.0 cm from the elbow joint, as shown in the figure(Figure 1) . The biceps, attached at a distance of 2.75 cm from the elbow, exerts an upward force on the forearm. Consider …
8. ### Physics

As a swimmer pulls his arm through the water, various muscles exert forces on the upper arm. The figure below shows a force F exerted on the humerus (upper arm bone) by the pectoral muscle. The muscle is connected to the bone d = 7.00 …
9. ### physics

A cook holds a 2.66-kg carton of milk at arm's length (see the figure below). What force B must be exerted by the biceps muscle?
10. ### Physics!!

An athlete at the gym holds a 5.54kg steel ball in his hand. His arm is 80.4cm long and has a mass of 4.26kg. What is the magnitude of the torque about his shoulder if he holds his arm straight out to his side, parallel to the floor?

More Similar Questions