Use the map to answer the question.

A pin-supported structure has unrestrained rotations at the support locations.a) True b) False

antoniya [11.8K]

Answer:

a)True

Explanation:

Yes it is true a pin support can not resist the rotation motion . It can resist only lateral or we can say that only linear motion of structure and can not resit angular moment of motion about hinge or pin joint.On the other hand a fixed support can resist linear as well rotation motion of structure.

6 0

3 years ago

If the atomic radius of copper is 0.128 nm, calculate the volume of its unit cell in cubic meters.

Alex_Xolod [135]

Answer:

Volume of face centered cubic cell= $4.74531*10^{-29} m^3$

Explanation:

Consider the face centered cubic cell:

1 atom at each corner of cube.

1 atom at center of each face.

Consider the one face (ABCD) as shown in attachment for calculation:

Length of the all sides of face centered cubic cell is L.

Volume of face centered cubic cell= L^3

Now Consider the figure shown in attachment:

According to Pythagoras theorem on ΔADC.

$L^{2}+L^2=(4a)^2$ (a is the atomic radius)

$L=\frac{4a}{\sqrt{2}}$ (Put in the formula of Volume)

Volume of face centered cubic cell= L^3

Volume of face centered cubic cell= $(\frac{4a}{\sqrt{2}})^3$

Volume of face centered cubic cell= $(\frac{4(0.128*10^{-9}}{\sqrt{2}})^3$

Volume of face centered cubic cell= $4.74531*10^{-29} m^3$

3 0

4 years ago

A small grinding wheel is attached to the shaft of an electric motor which has a rated speed of 3600 rpm. When the power is turn

Ostrovityanka [42]

Answer: a) 150 rev. b) 2105 rev.

Explanation:

a) Assuming a uniformly accelerated motion, we can use the equivalent kinematic equations, replacing linear variables by angular ones.

In order to get the number of revolutions executed, we can use this:

ωf² - ω₀² = 2 γ Δθ (1)

For the first part, we know that ω₀ = 0 (as it starts from rest).

We can find out the value of angular acceleration γ, just applying the definition of angular acceleration, as the change in angular velocity, regarding time, as follows:

γ = (ωf - ω₀) / Δt (2)

As we would want to use SI units, it is advisable to convert the value of ωf, from rpm to rad/sec.

3600 rev/min . (1min/60 sec) . (2π rad/rev) = 120π rad/sec

Replacing in (2), we get γ:

γ = 120 π / 5 rad/sec² = 24 π rad/sec²

Replacing in (1) and solving for Δθ:

Δθ = 120² π² / 2. 24 π = 300 π rad

As 1 rev = 2π rad, Δθ = 150 rev

b) For the second part, we can use exactly the same equations, taking into account that ω₀ = 120 π rad/sec, and that ωf = 0.

The new value for γ is as follows:

γ = -120π / 70 rad/sec² = -1.71 rad/sec²

Replacing in (1) and solving for Δθ, we get:

Δθ = -120² π² / 2. (-1.71) π = 4210 π rad

As 1 rev = 2π rad, Δθ = 2105 rev

7 0

4 years ago

A cylindrical rod of a metal alloy is stressed elastically in tension. The original diameter was 11 mm and a force of 55 kN was

andrey2020 [161]

Answer:

10.984mm

Explanation:

by elastic modulus

stress=modulus of elasticity*strain

stress=loading/area area" cross-section"

11mm=0.011m

area=π(d/2)^2=π(0.011/2)^2=9.503*10^-5 square meter

stress=55000/(9.503*10^-5)=578.745 MPa

convert MPa and GPa to pascal.

strain=stress/modulus=(578.745*10^6)/(125*10^9)=0.00463............axial strain

v=Poisson ratio

lateral strain=(-v)*axial strain= -0.31*0.00463

lateral strain= -1.4353*10^-3=change in diameter/ original diameter

change in diameter=(-1.4353*10^-3)*0.011= -1.57883*10^-5 m

negative indicates decrease in diameter.

decrease in dia.=0.01578mm

new diameter=11-0.01578= 10.984mm

3 0

3 years ago

Climate change isn't just about temperature! The amount of rain and snow (precipitation) in certain regions of the U.S. is also

Umnica [9.8K]

If I had to guess, I'd say the answer is

Drier conditions will likely result in more wildfires

Studies show that warmer and drier areas will double in wildfires by 2050.

3 0

3 years ago