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faltersainse [42]
3 years ago
8

The force, F, of the wind blowing against a building is given by where V is the wind speed, rho the density of the air, A the cr

oss-sectional area of the building, and CD is a constant termed the drag coefficient. Determine the dimensions of the drag coefficient.
Physics
1 answer:
Sveta_85 [38]3 years ago
7 0

Answer:

dimensions of the drag coefficient is [M^0 L^0 T^0]

Drag coefficient is a dimensionless quantity

Explanation:

force is given byF=\frac{C_{D}  \rho V^2 A}{2}

we get expression for drag coefficient C_{D} =\frac{2F}{\rho V^2 A}

By substituting the dimensions  of the F,V,A and density , we get

C_{D} =\frac{[F]}{[\rho ][V]^2[A]} \\C_{D} =\frac{[MLT^{-2}]}{[ML^{-3} ][L T^{-1}]^2[L^2]} \\C_{D} =\frac{[MLT^{-2}]}{[ML^{-3} ][L^2 T^{-2}][L^2]} \\C_{D} =\frac{[MLT^{-2}]}{[MLT^{-2}]}\\C_{D}=[M^0 L^0 T^0]

Drag coefficient is a dimensionless

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attashe74 [19]
Mass of object/source
Gravity
Fg=mg
3 0
3 years ago
How much power is needed to lift a 20-kg object to a height of 4.0 m in 2.5 seconds?
4vir4ik [10]

Answer:

313.92w

Explanation:

Formula for power:

P=W/∆t = Fv

Givens:

m=20kg

∆y=4.0m

∆t=2.5s

a=9.81m/s²

In order to find power, we first need to solve for work.

W=Fd (force*displacement), f=mg

W=mg∆y

W=(20kg)(9.81m/s²)(4.0m)

W=784.8J

P=W/∆t

P=784.8J/2.5s

P=313.92 watts

5 0
3 years ago
Calculate the force at sea level that a boy of mass 50 kg exerts on a chair in which he is sitting.
kogti [31]

As per the question the mass of the boy is 50 kg.

The boy sits on a chair.

We are asked to calculate the force exerted by the boy on the chair at sea level.

The force exerted by boy on the chair while sitting on it is nothing else except the force of gravity of earth i.e the weight of the body .The direction of that force is vertically downward.

At sea level the acceleration due to gravity g = 9.8 m/s^2

Hence the weight of the boy w = mg  [m is the mass of the body]

we have m = 50 kg.

                             Hence w = 50 kg ×9.8 m/s^2

                                             =490 N kg m/s^2

                                              = 490 N

Here newton [N] is the unit of force.





6 0
3 years ago
Read 2 more answers
A powerful motorcycle can produce an acceleration of 3.00 m/s2 while traveling at 90.0 km/h. At that speed the forces resisting
nata0808 [166]

Answer:

1185 N

Explanation:

From Newton’s second law of motion,  

F=ma where m= mass of motorcycle, a is acceleration of the motorcycle and F=Force

Net force acting on motorcycle F_{net} is given by  F_{net}=F-f

Where F is force acting on motorcycle and f is frictional force

Substituting F-f for F_{net}

F_{net}=ma hence  ma= F- f Substituting a with 3, m with 245Kg and f with 450N as provided

245*3= F- 450

F=245*3 +450= 1185 N

6 0
3 years ago
Which of these is true about kinetic energy but not necessarily true about potential energy
cestrela7 [59]

Kinetic energy is never negative, but potential energy can be.

Potential energy depends on height above some reference level,
and you can pick any level you want as the reference.  So, if the
object is below the reference level you pick, then its potential
energy relative to your reference level is negative. 

What that means is:  You have to lift it / do work on it / give it more
energy than it has now ... in order to move it to the reference level.

(That's exactly the situation with electrons bound to an atom.  Their
energy is considered negative, because we have to do work and
give them more energy to rip them away from the atom.)
_____________________________________

Regarding the other choices:

-- Kinetic energy is scalar ... Yes.  So is potential energy.

-- Kinetic energy increases with height ...
   No. It doesn't, but potential energy does.

-- Kinetic energy depends on position ...
   No. It doesn't, but potential energy does.

3 0
3 years ago
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