Answer:
Minimum elastic modulus of fiber = 455.64 GPa
Explanation:
Contents of composite material = Epoxy and Unidirectional fibers
Elastic modulus of epoxy = 3.5 GPa
Elastic modulus of composite material = 320 GPa
Volume fraction of fiber = 70 %
Volume fraction of epoxy = 100 - 70 = 30%
Elastic modulus of composite material = 3.5 x 0.3 + Elastic modulus of fiber x 0.7 = 320
0.7 x Elastic modulus of fiber = 320 - 1.05 = 318.95
Elastic modulus of fiber = 455.64 GPa
Minimum elastic modulus of fiber = 455.64 GPa
Answer:
a) Revolutions per minute = 2.33
b) Centripetal acceleration = 11649.44 m/s²
Explanation:
a) Angular velocity is the ratio of linear velocity and radius.
Here linear velocity = 72 m/s
Radius, r = 0.89 x 0. 5 = 0.445 m
Angular velocity

Frequency

Revolutions per minute = 2.33
b) Centripetal acceleration

Here linear velocity = 72 m/s
Radius, r = 0.445 m
Substituting

Centripetal acceleration = 11649.44m/s²
Answer:
+16 J
Explanation:
We can solve the problem by using the 1st law of thermodynamics:

where
is the change of the internal energy of the system
Q is the heat (positive if supplied to the system, negative if dissipated by the system)
W is the work done (positive if done by the system, negative if done by the surroundings on the system)
In this case we have:
Q = -12 J is the heat dissipated by the system
W = -28 J is the work done ON the system
Substituting into the equation, we find the change in internal energy of the system:

The handle of a metal pot gets warm when the water inside the pot starts to boil