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Ymorist [56]
2 years ago
5

A crane lifts a concrete block, whose weight is 60,000N to a height of 20m in 30s.

Physics
1 answer:
Nataly_w [17]2 years ago
7 0

Answer:

C

Explanation:

Power formula is power=work(joules)/time(seconds). the Work formula is force (newtons) times the distance from the starting point. Calculate work first: 60,000N x20m = 1,200,000 joules. Then plug into power formula: 1,200,000j/ 30 seconds= 40,000 W

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a circular loop is hanging on the wall. it has a radius of 33.3 cm and is comprised of 12 coils. there is a magnetic field perpe
Vika [28.1K]

Answer:

I = 2.19A, anticlockwise direction.

Explanation:

Given r = 33cm = 0.33m, N = 12, ΔB = 7.5 - 1.5 = 6.0T, Δt = 3s, R = 3.75Ω

By Faraday's law of electromagnetic induction when there is a change in flux in a coil or loop, an emf is induced in the coil or loop which is proportional to the time rate of change of the magnetic flux through the loop.

The emf E is related to the flux by the formula

E = – NdФ/dt

Where N = number of turns in the coil, Ф = magnetic flux through the loop = BA, B = magnetic field strength, A = Area

In this problem the strength of the magnetic field changes. As a result the flux too changes and an emf is induced in the coil.

So

ΔФ = ΔB×A = ΔB×πr² = 6×π×0.33² = 2.05Wb

E = -NΔФ/Δt = 12×2.05/3 = 8.2V

I = E/R = 8.2/ 3.75 = 2.19A

The direction of the current can be found by pointing the thumb of your right hand in the direction of the magnetic field and curling the remaining fingers around this direction. The direction of the curl of these fingers give the direction of current which in this case is anticlockwise.

5 0
3 years ago
Why is it advised not to hold the thermometer by its bulb while reading it?
Fiesta28 [93]
Because your body heat might change the temperature
7 0
2 years ago
Read 2 more answers
Which of the following is not a unit of volume?
fiasKO [112]
Cm2 it is unit of area not volume
4 0
3 years ago
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An ac source of period T and maximum voltage V is connected to a single unknown ideal element that is either a resistor, and ind
stepladder [879]

Answer:

Capacitor, is the right answer.

Explanation:

The unknown element is a Capacitor.

Below is the calculation that proves that it is a capacitor.

We know that for the Capacitor

i = Imax × sin(wt+(pi/2)).

i = Imax × sin ((2 × pi/T) × (T/4) + (pi/2))

i = Imax × sin(3.142) = 0 A

at, t = T/2

wt = (2 × pi/T) × (T/2) = pi

wt + (pi/2) = pi + (pi/2) = ( 3 × pi/2) =

i = Imax × sin(3 × pi/2) = -Imax

Which is in a correct agreement with capacitor  therefore, the answer is a Capacitor.

5 0
3 years ago
A player kicks a soccer ball in a high arc toward the opponent's goal. When the soccer ball reaches its maximum height, how does
Artyom0805 [142]

Answer:

The speed of the soccer ball at height point is less than its initial speed

Explanation:

The initial velocity of the soccer can be written in vector form as

v_{i = v cos θ î + v sin θ j

where v_{i  is initial velocity of the ball

           v is the initial speed of the ball

Assume soccer ball is kicked at an angle θ with an horizontal and initial speed vm/s. Its horizontal component will be as,

v_{x} = v cos θ

v_{y} = v sin θ

At the maximum height, the vertical component becomes zero. therefore, the velocity of the soccer at the maximum point can be written as,

v_{m} = v cos θ j

where, v_{m} is velocity of the soccer ball at maximum height

5 0
3 years ago
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