Answer / Explanation:
To properly answer this question, let us define what a grain boundary is:
A grain boundary is the interface between multiple grains or crystals in a poly-crystalline material. They could also be refereed to as defects in the crystal structure and tend to decrease the electrical and thermal conductivity of structures.
Now, if we refer back to the question asked,
(a) The surface energy is grater than the grain boundary energy because surface atom have fewer bonds than atom along a grain boundary.
Consequentially, the lower the number of bonds formed, the higher the energy
(b) A higher angle grain boundary has higher misalignment and hence greater disruption of bonds (lesser number of bonds) than a small angle grain boundary. Therefore, a high angle grain boundary has higher energy.
By definition we have that the linear moment is
p = m * v
Where
m = mass
v = speed.
Clearing the mass we have
m = p / v
Substituting the values
m= (13,300 kgm/s)/(14 m/s)=950Kg
the mass of the car is 950 Kg
Answer:
Option B is the correct answer.
Explanation:
Let us consider 40 meter above ground as origin.
Initial velocity = 17 m/s
Final velocity = 24 m/s
Acceleration = 9.81 m/s
We have equation of motion v² = u² + 2as
Substituting
24² = 17² + 2 x 9.81 x s
s = 14.63 m
Distance traveled by rock = 14.63 m down.
Height of rock from ground = 40 - 14.63 = 25.37 m = 25.4 m
Option B is the correct answer.
