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vladimir1956
2 months ago
7

A spherical hot-air balloon is initially filled with air at 120 kPa and 20°C with an initial diameter of 5 m. Air enters this ba

lloon at 120 kPa and 20°C with a velocity of 3 m/s through a 1-m-diameter opening. How many minutes will it take to inflate this balloon to a 17-m diameter when the pres-sure and temperature of the air in the balloon remain the same as the air entering the balloon?
Engineering
1 answer:
mote1985 [299]2 months ago
8 0

Answer:

The duration is 17.43 minutes.

Explanation:

Based on the provided information, the initial diameter is 5 m

the velocity is 3 m/s

and the final diameter is 17 m.

To find the solution, we will use the volume change equation expressed as

ΔV = \frac{4}{3} \pi * (rf)^3 - \frac{4}{3} \pi * (ri)^3.............1

where ΔV represents the change in volume, rf is the final radius, and ri is the initial radius.

Calculating ΔV yields

ΔV = \frac{4}{3} \pi * (8.5)^3 - \frac{4}{3} \pi * (2.5)^3

ΔV = 2507 m³.

Thus,

Q = velocity × Area

Q = 3 × π ×(0.5)² = 2.356 m³/s.

Next, the change in time can be expressed as

Δt = \frac{\Delta V}{Q}

Δt = \frac{2507}{2.356}

Δt = 1046 seconds.

Therefore, the total change in time amounts to 17.43 minutes.

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There are five distinct types of fire extinguishers, each identifiable by specific color codes.

Red - Water-based

Creme - Foam-based

Blue - Powder-based

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Yellow - Wet chemical-based

The type of fire extinguisher required is determined by the class of fire being dealt with.

Class A - Combustible materials (e.g., paper, wood) Recommended extinguishers - Red, Creme, Blue, and Yellow. (Avoid using Black)

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8 0
1 month ago
Read 2 more answers
A test machine that kicks soccer balls has a 5-lb simulated foot attached to the end of a 6-ft long pendulum arm of negligible m
choli [298]

Answer:

a) v₂ = 26.6 ft/s

b) v₂ = 31.9 ft/s

Explanation:

a) Applying the principle of energy conservation for the soccer arm from the point of impact to its lowest point:

mgh=\frac{1}{2} mv^{2} \\v=\sqrt{2gh} =\sqrt{2*32.2*6} =19.66ft/s

The ball's velocity in the tangential direction is given by:

v₂*sinθ = v₁*sin30

With the values:

if v₁ = 0

θ = 0º

The restitution coefficient is:

e=\frac{v_{2}*cosO-v_{2}cos30 }{v*cos30-(-v_{1}*cos30 )} \\0.8=\frac{v_{2}cos0-v_{2}*cos30 }{19.66*cos30-(0*cos30)} \\v_{2} =\frac{v_{2}-13.6 }{cos30}

where O=θ

The aggregate momentum equation is:

mv-mv_{1} =mv_{2} +mv_{2} cos(O+30)\\, where O = θ

mv-mv_{1} =m(\frac{v_{2}-13.6 }{cos30} )+mv_{2} cos(O+30)

When we incorporate gravitational acceleration:

mgv-mgv_{1} =mg(\frac{v_{2}-13.6 }{cos30} )+mgv_{2} cos(O+30)\\5*19.66-1*0=5*(\frac{v_{2}-13.6 }{cos30} )+1*v_{2} cos(O+30)

Isolating v₂ results in:

v₂ = 26.6 ft/s

b) To find the ball's velocity, we utilize:

v₂ * sinθ = v₁ * sin30

if v₁ = 10 ft/s

then v₂ * sinθ = 10 * sin30

thus sinθ = 5/v₂

The restitution coefficient remains:

e=\frac{v_{2}*cosO-v_{2}cos30 }{v*cos30-(-v_{2}*cos30) } \\0.8=\frac{v_{2}cosO-v_{2}cos30 }{19.66*cos30-(-10*cos30)} \\v_{2} =\frac{v_{2}cos30-20.55}{cos30}

where O = θ

mgv-mgv_{1} =mgv_{2} +mgv_{2} cos(O+30)\\5*19.66-1*0=5v_{2} +v_{2} cos(O+30)\\98.3=5v_{2}+v_{2} cosOcos30-v_{2} sinOsin30

Solving for v₂ yields:

v₂ = 31.9 ft/s

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iogann1982 [368]

Answer:

153.2 J

Explanation:

Let’s first identify our known variables:

mass (m) of the block = 10 kg

distance slid down (i.e., displacement) = 2 m

coefficient of kinetic friction (μk) = 0.2

In the following diagram, if we analyze the force component directed along the displacement, we find

F_x= Fcos 40°

F_x= 100 (cos 40°)

F_x= 76.60 N

The work done by the frictional force is then calculated as:

W = F_x × displacement

W = 76.60 × 2

W = 153.2 J

Therefore, the work done by the frictional force equals 153.2 J

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