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3 years ago

15

Using 1000 j of work, a toy elevator is raised from the ground floor to the second floor in 20 s. how much power does the elevat

or use?

1 answer:

Anastasy [175]3 years ago

3 0

Power (watts) = work done (joules) ÷ time (seconds)

power (watts) = 1000J ÷ 20s

power (watts) = 50w

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How many forces are acting on a stationary raft floating in a swimming pool A1 B2 or C3

Hitman42 [59]

There are at least two forces on it, and there could be more.

Vertical forces:
-- gravity, directed downward
-- buoyant force, directed upward
These two forces must be exactly equal, so that the net
vertical force on the raft is zero. Otherwise, it would be
accelerating either up or down.

Horizontal forces:
We know that the net horizontal force on the raft is zero.
Otherwise, it would be accelerating horizontally.

But we don't know if there are actually no horizontal forces
at all, or a balanced group of horizontal forces, that add up
to a net force of zero.

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3 years ago

A 32.5 g cube of aluminum initially at 45.8 °C is submerged into 105.3 g of water at 15.4 °C. What is the final temperature of b

lakkis [162]

Answer:

$T = 17.26 ^oC$

Explanation:

At thermal equilibrium we have heat given by aluminium must be equal to the heat absorbed by the water

so we will have

$Q_1 = Q_2$

$m_1s_1\Delta T_1 = m_2s_2\Delta T_2$

so we will have

$32.5(900)(45.8 - T) = 105.3(4186)(T - 15.4)$

so we have

$(45.8 - T) = 15.1(T - 15.4)$

so we have

$16.1 T = 277.87$

$T = 17.26 ^oC$

6 0

3 years ago

What is the speed of a car that travels 48 km in 2 hours?

ankoles [38]

Speed=distance/time

distance =48km
time=2 hours

speed=48/2
=24km/h

speed=24km/h

FORMULAS

speed = distance/time
time = distance/speed
distance = speed×time

3 0

3 years ago

An emf is induced in a conducting loop of wire 1.22 m long as its shape is changed from square to circular. Find the average mag

Afina-wow [57]

Answer:

The induced emf in the loop is $7.35\times 10^{-4}\ V$

Explanation:

Given that,

Length of the wire, L = 1.22 m

It changes its shape is changed from square to circular. Then the side of square be its circumference, 4a = L

4a = 1.22

a = 0.305 m

Area of square, $A=a^2=(0.305)^2=0.0930\ m^2$

Circumference of the loop,

$C=2\pi r=L\\\\r=\dfrac{L}{2\pi}\\\\r=\dfrac{1.22}{2\pi}=0.194\ m$

Area of circle,

$A'=\pi r^2\\A'=\pi (0.194)^2\\\\A'=0.118\ m^2$

The induced emf is given by :

$\epsilon=\dfrac{\d\phi}{dt}\\\\\epsilon=\dfrac{\d(BA)}{dt}\\\\\epsilon=B\dfrac{A'-A}{t}\\\\\epsilon=0.125 \times \dfrac{0.118-0.0930}{4.25}\\\\\epsilon=7.35\times 10^{-4}\ V$

So, the induced emf in the loop is $7.35\times 10^{-4}\ V$

8 0

3 years ago

When light in vacuum is incident at the polarizing angle (Brewster's angle) on a certain glass slab, the angle of refraction is

marysya [2.9K]

Answer:

Explanation:

θ( p ) + θ( r ) = 90

θ (r) = angle of refraction and θ ( p ) is polarising angle.

given θ ( r ) = 31.8

θ ( p ) = 90 - 31.8 = 58.2 degree

ii ) Tanθ ( p ) = n ( refractive index ) = Tan 58.2 = 1.6

3 0

3 years ago