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Kay [80]
3 years ago
9

A ski lift carries a 75.0-kg skier at 3.00 m/s for 1.50 min along a cable that is inclined at an angle of 40.0° above the horizo

ntal. a. How much work is done by the ski lift? b. How much power is expended by the ski lift?
Physics
1 answer:
Nookie1986 [14]3 years ago
3 0

Answer

given,

mass of the ski = 75 Kg

speed of the skier, v = 3 m/s

time = 1.50 min = 90 s

angle of inclination, θ = 40°

distance = s x t

              = 3 x 90 = 270 m

a) W = F. d cos θ

   W = mg. d cos θ

   W = 75 x 9.8 x 270 x cos 40°

    W = 152021.52 J

work is done by the ski lift is equal to  152021.52 J

b) Power extended by the ski

 Power = \dfrac{Work\ done}{time}

Power = \dfrac{152021.52}{90}

      P = 1689.13 Watt.

power is expended by the ski lift is equal to 1689.13 W.

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A 77.0 kg woman slides down a 42.6 m long waterslide inclined at 42.3. at the bottom, she is moving 20.3 m/s.how much work did f
zhuklara [117]

Answer:

5.791244495 KNm

Explanation:

The height h is given by, h=42.6sin42.3^{o}

Potential energy, PE is given by

PE=mgh where m is mass of the woman, g is acceleration due to gravity whose value is taken as 9.81 m/s^{2} and h is already given hence substituting 77 Kg for m we obtain

PE=77*9.81*42.6sin42.3^{o}=21656.7095 Nm

PE=21.6567095 KNm

We also know that Kinetic energy is given by0.5mv^{2} where v is the velocity and substituting v for 20.3 we obtain

KE=0.5*77*20.3^{2}=15865.465 Nm

KE=15.865465 KNm

Friction work is the difference between PE and KE hence

Friction work=21.6567095 KNm-15865.465 Nm=5.791244495 KNm

8 0
3 years ago
In an experiment, 108 J of work was done on a closed system. During this phase of the experiment, 79 J of heat energy was added
amid [387]

Answer:

187 J

Explanation:

First Law of Thermodynamics :

ΔQ = ΔW + ΔU

ΔQ : Heat. If it added to system then positive and if it is rejected by system then negative.

ΔW : Work. If it done by the system then positive and if it is done on system then negative.

ΔU : Internal Energy. If it positive then temperature of system increased and if it is negative then temperature of system decreased.

ΔQ = 79 J

ΔW = - 108 J

ΔU = ?

substituting the value in the equation:

79 = -108 + ΔU

∴ ΔU = 187 J

7 0
3 years ago
Choose the sequence of energy forms that best fits each item.
levacccp [35]

Answer:

1. chemical energy --> electrical energy --> light energy

2. Electrical Energy --> Mechanical Energy

3. Electrical Energy --> Heat Energy

4. Chemical Energy --> Thermal Energy  --> Mechanical Energy

5. Nuclear Energy --> Light energy and thermal energy

6. Mechanical Energy --> Electric Energy

7. Chemical Energy --> Electrical Energy --> Sound Energy

8. Mechanical Energy --> Sound Energy

Explanation:

1.<u>FLASHLIGHT</u>:

chemical energy --> electrical energy --> light energy

The chemical energy from the cell batteries is converted to electrical energy, which is used to produce the light energy in form of flashlight.

2.<u>ELECTRIC SAW</u>:

Electrical Energy --> Mechanical Energy

The electrical energy from the socket is converted to the mechanical energy used to run the saw blade.

3.<u>TOASTER</u>:

Electrical Energy --> Heat Energy

The electrical energy from the socket is converted to the heat energy (thermal energy) used in browning the bread.

4.<u>GAS POWERED SCOOTER</u>:

Chemical Energy --> Thermal Energy  --> Mechanical Energy

The chemical energy from fuel, such as petrol is converted to heat (thermal energy) in the engine by the process of combustion. This heat is then used to do work by conversion into mechanical energy, through piston movement, which in turn moves the shaft and the scooter.

5.<u>THE SUN</u>:

Nuclear Energy --> Light energy and thermal energy

The nuclear reactions on Sun provide nuclear energy which is converted into light and thermal energy that reaches us on earth.

6.<u>WIND TURBINE</u>:

Mechanical Energy --> Electric Energy

The mechanical energy is provided by wind when it rotates the blade of turbine. This is then converted to electrical energy b the turbine.

7.<u>IPOD</u>:

Chemical Energy --> Electrical Energy --> Sound Energy

The chemical energy i supplied by the battery of ipod, which is converted to electrical energy and that electrical energy is used to produce sound by ipod.

8.<u>SPEAKER VIBRATES</u>

Mechanical Energy --> Sound Energy

The mechanical energy due to vibration produces sound energy.

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