A lead brick with the dimensions shown in the figure below (6.0 cm left to right

Physics
Tutor: None Selected Time limit: 1 Day

Apr 16th, 2015

The force on the brick is 2750N
This has a vertical component (Fv) of 2750 * Sin(27) 
= 1248.47 N 

and a horizontal component (Fh) of 2750 * Cos(27) 
= 2450.27 N 

We have to assume that the lead brick will undergo elastic deformation rather than plastic deformation. 

(a) 
Young's modulus for Lead is 16 GPa 

= Fv * h / (A * dh) 

where h is the height = 0.02 m 
A is the top area = 0.06 * 0.05 = 0.003 m^2 
dh = the change in height 

16 * 10^9 = 1248.47 * 0.02 / (0.003 * dh) 

dh = 1248.47 * 0.02 / (0.003 * 16 * 10^9) 
= 5.2*10^(-7)

(b) 
Shear modulus for Lead = 5.6 GPa 

= Fh * h / (A * dx) 

where dx is the amount the top surface will move horizontally because of the defromation (from Wikipedia) 

5.6 * 10^9 = 2450.27 * 0.02 / (0.003 * dx) 

dx = 2450.27 * 0.02 / (0.003 * 5.6 * 10^9) 
= 2.92 *19^-6

Apr 16th, 2015

the answers were incorrect


Apr 16th, 2015

The force on the brick is 2750N
This has a vertical component (Fv) of 2750 * Sin(21)
= 985.51 N 

and a horizontal component (Fh) of 2750 * Cos(21)
= 2567.35 N 

We have to assume that the lead brick will undergo elastic deformation rather than plastic deformation. 

(a) 
Young's modulus for Lead is 16 GPa 

= Fv * h / (A * dh) 

where h is the height = 0.02 m 
A is the top area = 0.06 * 0.05 = 0.003 m^2 
dh = the change in height 

16 * 10^9 = 985.51 0.02 / (0.003 * dh) 

dh = 985.51 0.02 / (0.003 * 16 * 10^9) 
= 4.11*10^-7

(b) 
Shear modulus for Lead = 5.6 GPa 

= Fh * h / (A * dx) 

where dx is the amount the top surface will move horizontally because of the defromation (from Wikipedia) 

5.6 * 10^9 = 2567.35 0.02 / (0.003 * dx) 

dx = 2567.35 0.02 / (0.003 * 5.6 * 10^9) 
= 3.1*10^-6

Apr 16th, 2015

it is still incorrect :(

Apr 16th, 2015

Are you studying on the go? Check out our FREE app and post questions on the fly!
Download on the
App Store
...
Apr 16th, 2015
...
Apr 16th, 2015
Dec 11th, 2016
check_circle
Mark as Final Answer
check_circle
Unmark as Final Answer
check_circle
Final Answer

Secure Information

Content will be erased after question is completed.

check_circle
Final Answer