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Ilia_Sergeevich [38]
3 years ago
8

A car is being lifted by a crane so that it moves upwards at a constant speed.

Physics
1 answer:
anygoal [31]3 years ago
7 0

Answer:

Explanation:

Work done is defined as the product of force and the displacement in the direction of force.

W = F x d x Cos θ

Where, θ be the angle between force and the displacement.

The force of gravity acts downwards and the displacement is in upward, so the angle is 180. cos 180 = -1 , so the work done by the force of gravity is negative.

The force of rope acting in upwards direction and displacement also in upwards direction.

So, the work done is positive

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Explain briefly how solar energy is used to generate electricity
valkas [14]

Answer:

Solar radiation may be converted directly into electricity by solar cells (photovoltaic cells). In such cells, a small electric voltage is generated when light strikes the junction between a metal and a semiconductor (such as silicon) or the junction between two different semiconductors.

Explanation:

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7 0
2 years ago
The amount of light lost within a fiber-optic system is known as
densk [106]
Attenuation is the correct answer. 
6 0
3 years ago
Suppose a 48-N sled is resting on packed snow. The coefficient of kinetic friction is 0.10. If a person weighing 660 N sits on t
Annette [7]

Assume the snow is uniform, and horizontal.

Given:

coefficient of kinetic friction = 0.10 = muK

weight of sled = 48 N

weight of rider = 660 N

normal force on of sled with rider = 48+660 N = 708 N = N

Force required to maintain a uniform speed

= coefficient of kinetic friction * normal force

= muK * N

= 0.10 * 708 N

=70.8 N


Note: it takes more than 70.8 N to start the sled in motion, because static friction is in general greater than kinetic friction.


8 0
3 years ago
Consider a short time span just before and after the spark plug in a gasoline engine ignites the fuel-air mixture and releases 1
Tju [1.3M]

Answer:

Temperature after ignition=7883.205 K

Explanation:

The number of moles is,

n=PV/RT

=(1.18x10^6)(47.9x10^-6)/8.314(325)

= 0.0209 moles

a) In this process volume is constant

Q=U

=nCv.dT

dT= Q/nCv

=1970/(1.5x8.314)(0.0209)

= 7558.205 K

The final temperature is,

= 7558.205+325

= 7883.205 K

5 0
3 years ago
Read 2 more answers
Beams used in Heavy Timber construction are sometimes firecut. This is done to: a) allow air circulation at the beam’s end in an
ladessa [460]

Answer:

option C

Explanation:

The correct answer is option C

Fire cut of fireman cut is diagonal cut which is provided at the end of the beam to prevent the fall of masonry wall if a fire breaks out in the building.

Fire cut allows joist to leave if it fails without affecting the masonry wall standing.

Without fire cut, the burnt beam will rotate downward affecting the connection of beam and wall and leading to damage it.

8 0
3 years ago
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