I believe a physical change is one where the physical makeup of a substance is altered as opposed to a chemical change or molecular one which happens on a smaller scale. This would make me think that B. metal denting is accurate since all the other options are examples of chemical or molecular changes. A is an example of a liquid turning into a gas, which is a molecular change. The other two are chemical changes. Hope this is correct.
Answer:
It would because the shape of the rocket is designed to be able to slice through the air as smooth as possible and now you may be thinking that air is already smooth but when you try to push something as large and heavy like a rocket then the shape of the rocket will be very important. The bottom of the rocket is flatter then the top so it is not designed to fly smoothly through the air. So the rocket would fall vertically downward(If it was still in one piece)because of it's shape. It is easier for the top of the rocket to go smoothly through the air then the bottom.
Explanation:
I am 90% sure this is correct but if I'm not please tell me
Answer:
a) 
b) 
c) Q = 1.256 × 10⁻³ m³/s
Explanation:
Given:
The velocity profile as:
Now, the maximum velocity of the flow is obtained at the center of the pipe
i.e r = 0
thus,
or
Now,
or
or
Now, the flow rate is given as:
Q = Area of cross-section of pipe × 
or
Q = 
or
Q = 
or
Q = 1.256 × 10⁻³ m³/s
From conservation of momentum, the ram force can be calculated similarly to rocket thrust:
F = d(mv)/dt = vdm/dt.
<span>In other words, the force needed to decelerate the wind equals the force that would be needed to produce it.
</span><span> v = 120/3.6 = 33.33 m/s
</span><span> dm/dt = v*area*density
</span> dm/dt = (33.33)*((45)*(75))*(1.3)
dm/dt = <span>
146235.375 </span><span>kg/s
</span><span> F = v^2*area*density
</span> F = (33.33)^2*((45)*(75))*(1.3) = <span>
<span>4874025 </span></span><span>N
</span> This differs by a factor of 2 from Bernoulli's equation, which relates velocity and pressure difference in reference not to a head-on collision of the fluid with a surface but to a fluid moving tangentially to the surface. Also, a typical mass-based drag equation, like Bernoulli's equation, has a coefficient of 1/2; however, it refers to a body moving through a fluid, where the fluid encountered by the body is not stopped relative to the body (i.e., brought up to its speed) like is the case in this problem.
The period is the temporal difference between two same points in consecutive waves
