Answer:
(D) 96 kg-m/s
Explanation:
Let's start off by first calculating the normal force between the box and the floor.
This will be:
Normal Force = 12 * 9.81 = 117.72 N
We can now use the friction equation to find the frictional force on the box when it is moving:
Frictional force = Coefficient of friction * Normal Force
Frictional force = 0.4 * 117.72 = 47.09 N
Finally, since we have the force on the box, we can find the acceleration:
F = Mass * Acceleration
47.09 = 12 * Acceleration
Acceleration = 3.92 m/s^2
Final speed after 2 seconds:
V= -3.84 m/s
Since we know the initial and final speeds, we can calculate the change in momentum:
Change in momentum = Final Momentum - Initial Momentum
Change in momentum = 
Change in momentum = 94.08 kg*m/s
Thus we can see that option (D) is the closest answer.
Answer:
The stars are moving away from us.
Explanation:
The observed wavelengths of hydrogen transition for stars A and B (660.0 nm and 666 nm respectively) are greater than that observed in the laboratory (656.2 nm). The observed long wavelengths for the stars means that the light from the stars is red-shifted.
According to the Doppler effect, red-shifted light means that the source is moving a way from the observer; therefore, we arrive at the conclusion that the stars A and B are moving away from us.
Answer:
This value is less than the maximum tension of 500 lbs, making it safe for man to go to the tip flap
Explanation:
We must work on this problem using the rotational equilibrium equations and then they compared the tension values that the cable supports.
Let's start with fixing a reference system on the hinge of the flag, we take as positive the anti-clockwise turn
They indicate the weight of the pole W₁ = 120 lb and a length of L = 9 ft, the weight of the man W₂ = 150, we assume that the cable is at the tip of the pole
- 
L + W₂ L + W₁ L / 2 = 0
T_{y} = W₂ + W₁ / 2
T_{y} = 120 + 150/2
T_{y} = 195 lb
we use trigonometry to find the cable tension
sin 30 = T_{y} / T
T = T_{y} / sin 30
T = 195 / sin 30
T = 390 lb
This value is less than the maximum tension of 500 lbs, making it safe for man to go to the tip flap
T < 500 lb
Answer: It will be take 2.6 hours
Explanation: Please see the attachments below
Answer:
The distribution is as depicted in the attached figure.
Explanation:
From the given data
- The plane wall is initially with constant properties is initially at a uniform temperature, To.
- Suddenly the surface x=L is exposed to convection process such that T∞>To.
- The other surface x=0 is maintained at To
- Uniform volumetric heating q' such that the steady state temperature exceeds T∞.
Assumptions which are valid are
- There is only conduction in 1-D.
- The system bears constant properties.
- The volumetric heat generation is uniform
From the given data, the condition are as follows
<u>Initial Condition</u>
At t≤0
This indicates that initially the temperature distribution was independent of x and is indicated as a straight line.
<u>Boundary Conditions</u>
<u>At x=0</u>
<u />
<u />
This indicates that the temperature on the x=0 plane will be equal to To which will rise further due to the volumetric heat generation.
<u>At x=L</u>
<u />![-k\frac{\partial T}{\partial x}]_{x=L}=h[T(L,t)-T_{\infty}]](https://tex.z-dn.net/?f=-k%5Cfrac%7B%5Cpartial%20T%7D%7B%5Cpartial%20x%7D%5D_%7Bx%3DL%7D%3Dh%5BT%28L%2Ct%29-T_%7B%5Cinfty%7D%5D)
<u />
This indicates that at the time t, the rate of conduction and the rate of convection will be equal at x=L.
The temperature distribution along with the schematics are given in the attached figure.
Further the heat flux is inferred from the temperature distribution using the Fourier law and is also as in the attached figure.
It is important to note that as T(x,∞)>T∞ and T∞>To thus the heat on both the boundaries will flow away from the wall.
