Solve Torque Problems with Expert Help - Homework Question Included"

[letsfailsafe]

Homework Statement

Questions are included in the photo

Homework Equations

The Attempt at a Solution

 

[Basic_Physics]

11. There are 3 torques acting on the beam. The sum of these need to be zero.

 

[aralbrec]

You should be showing an attempt to a solution before getting help but I'll get you started.

Both questions rely on the same thing: information has been provided to locate the center of mass of the beam (11) and the broom (12).

 

[letsfailsafe]

For question 11.

Total clockwise t = total anti clock wise t
(10 x 3) = (28 x 2) (Fb x ??)

Total tension will be: 28N + 10N + Beam weight force (?)
Problem here is that I don't know the weight force of the beam...

That was my attempt before I post this online...For question 12.

Total support force for a finger must be: (1.5 x 9.8) + (0.4 x 9.8) = 18.62N (?)
I can solve this question if I knew where any two forces were being applied...

 

[Basic_Physics]

Total clockwise t = total anti clock wise t
(10 x 3) = (28 x 2) (Fb x ??)
I assume Fb is the weight of the beam. Its torque will act in the middle of the beam.

 

[letsfailsafe]

Total clockwise t = total anti clock wise t
(10 x 3) = (28 x 2) (Fb x ??)
I assume Fb is the weight of the beam. Its torque will act in the middle of the beam.

Using point X as the pivot point then:

Total clock wise t = total anti clock wise t
(Fb x 1.5) + (10 x 3) = (28 x 2)
1.5 Fb + 30 = 56
1.5 Fb = 56 -30
Fb = (56-30)/1.5 = 17.3333

17.33N

The answer says 52N...

 

[Basic_Physics]

The distance to the middle is 0.5 not 1.5

 

[letsfailsafe]

The distance to the middle is 0.5 not 1.5

Oh man... stupid mistake... please help me do the question 12!

 

[bsbs]

question 12!

total mass 1.5kg
center of mass at 1.4m
imagine the broom is a 2.8m rod instead.

if you add 0.4kg to one side, what is the distance that you need to move from the center, in order to balance the rod.

a logical answer will be <1.4m

 

[letsfailsafe]

total mass 1.5kg
center of mass at 1.4m
imagine the broom is a 2.8m rod instead.

if you add 0.4kg to one side, what is the distance that you need to move from the center, in order to balance the rod.

a logical answer will be <1.4m

The answer says its 1.1m...

 

[Basic_Physics]

The centre of gravity or centre of mass is located at 1.4 meter. If it was not the broom would have rotated off her finger. She would need to balance it a bit to the right of this point with the additional 400 gram. Call this distance x and recalculate about this new point .

 

[bsbs]

The answer says its 1.1m...

this answer is correct,

next hint,
half of 1.5kg is 0.75 kg
if center is 1.4m, you will need another 1.4m to make this statement true, 2.8m
add 0.4kg to 1.5kg, which make this broom now 1.9kg

with these 3 values, you can easily work the answer as 1.1m