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MArishka [77]
2 years ago
5

A Styrofoam slab has thickness h and density ρs. When a swimmer of mass m is resting on it, the slab floats in fresh water with

its top at the same level as the water surface. Find the area of the slab. (Use any variable or symbol stated above along with the following as necessary: ρw for the density of water.)
Physics
1 answer:
sattari [20]2 years ago
8 0
 <span>A = area of styrofoam 
M = mass of stryofoam = A*h*rho_s 
m = mass of swimmer 

Total mass = m + M = m + A*h*rho_s 
Downward force = g*(total mass) = g*[m + A*h*rho_s] 

The slab is completely submerged. 
Buoyant force = g*(mass of water displaced) = g*[A*h*rho_w] 

Equate these 
g*[m + A*h*rho_s] = g*[A*h*rho_w] 
m + A*h*rho_s = A*h*rho_w 
A*h*[rho_w - rho_s] = m 
A = m/[h*(rho_w - rho_s)]</span>
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Jordan wants to know the difference between using a 60-W and 100-W lightbulb in her lamp. She calculates the energy it would tak
Andreas93 [3]

Answer:

The difference in the amount of energy transferred by the two bulbs is 1200 J.

Explanation:

The energy transferred by the two lightbulbs can be calculated with the given equation:

E = P*t

Where P is the power and t is the time

For the 60 W lightbulb:

E_{60} = P*t = 60 W*30 s = 1800 J

For the 100 W lightbulb:

E_{100} = P*t = 100 W*30 s = 3000 J

Hence, the difference in the amount of energy transferred is:

E_{t} = E_{100} - E_{60} = 3000 J - 1800 J = 1200 J

Therefore, the difference in the amount of energy transferred by the two bulbs is 1200 J.

I hope it helps you!

4 0
2 years ago
A wind turbine with a rotor diameter of 40 m produces 90 kW of electrical power when the wind speed is 8 m/s. The density of air
aleksley [76]

Answer:

0.233

Explanation:

Given that

Diameter of rotor, d = 40 m

Power of rotor, P = 90 kW

Speed of the wind, v = 8 m/s

Density of air, p = 1.2 kg/m³

It is a known fact that

KE = ½mv², where mass flow rate, m

m = p.A.v, where Area, A

A = πd²/4

A = (3.142 * 40²)/4

A = 3.142 * 1600/4

A = 3.142 * 400

A = 1256.8 m², substitute for A in the mass flow rate equation

m = p.A.v

m = 1.2 * 1256.8 * 8

m = 12065.28, substitute for m in the KE equation

KE = ½mv²

KE = ½ * 12065.28 * 8²

KE = 12065.28 * 32

KE = 386088.96 W or

KE = 386.1 kW

Fraction of kinetic energy converted to electric energy is

Fraction = Electric Power / Total KE

Fraction = 90 / 386.1

Fraction = 0.233

8 0
2 years ago
A 3030 cmcm wrench is used to loosen a bolt with a force applied 0.30.3 mm from the bolt. It takes 6060 NN to loosen the bolt wh
kolezko [41]

Complete Question

A 30 cmcm wrench is used to loosen a bolt with a force applied 0.30m from the bolt. It takes 60 N to loosen the bolt when the force is applied perpendicular to the wrench. How much force would it take if the force was applied at a 30 degree angle from perpendicular?

Answer:

The force required is  F_{\theta }  =    69.28 \ N

Explanation:

From the question we are told that

    The length of the wrench is L  =  30 cm =  \frac{30}{100} =  0.3 \ m

    The distance from the bolt is  d = 0.30 m

      The force it takes to loosen the bolt is F  =  60 N

       The angle of application is \theta = 30 ^o

Generally the torque required to loosen the bolt is

       \tau =  F * d

        \tau =  60 * 0.3

        \tau =  18 Nm

Now for the bolt to be loosen at \theta the torque at 90° must be the same as that at \theta

So the torque at  \theta is mathematically represented as

          \tau   =  F_{\theta }d  cos \theta

substituting values

           18 =  F_{\theta } * 0.3  cos (30)

           F_{\theta }  =    \frac{18}{0.3  cos (30)}

           F_{\theta }  =    69.28 \ N

       

7 0
2 years ago
A baseball weighs 5.19 oz. what is the kinetic energy, in joules, of this baseball when it is thrown by a major-league pitcher a
Stels [109]
Kinetic energy =0.5*mas*velocity^2
Joules =lg*m^2/s^2
1 miles= 1608.34 meters
1 hour= 3600 Sec
1 ounce =28.35g =0.02836 kg
What is a the kinetic energy, in joules, of this baseball when it is thrown by a major-league pitcher at 96.0 mi/h?

Answer: KE=0.5m*v^2
=0.5*(5.12 o *0.02835 kg/1 ounce)* (95 miles/h*1609.34m/1 miles* 1hr/3600s^)2
131kg*m^2/s^2= 131 joules

By what factor with the kinetic energy change if the speed of the baseball is decreased to 55.0 mi/h?

Answer: KE=0.5*m*v^2
=0.5*(5.13 o*0.02835kg/1 ounce)*(55 miles/ h*1609.34m/1 mile*1 hr/3600s)^2
=44.0kg*m^2s^2=44.0 joules

131/44= 2.98, so decreased by a factor of approximately 3



7 0
1 year ago
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Arrange the movement/act/organization in ascending order of occurrence. Energy Supply and Environmental Coordination Act Nature
nadya68 [22]

Answer:

PLATO!!!!! THESE ARE RIGHT!!! OTHERS ARE NOT CORRECT. I JUST GOT IT RIGHT ON PLATO

Explanation:

1. federal water pollution control act

2.nature conservancy

3. clean air act

4. water quality act

5. endangered species preservation act

6. clean water act

7. energy supply and environmental coordination act

8. eastern wilderness act

9. toxic substance act

10. intergovernmental panel on climate change (IPCC).

5 0
2 years ago
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