Ask question

Ask question

All categories

4 years ago

7

Calculate the energy in kilowatt hours used by a heater that operates continuously for 30 minutes. The heater has a power rating

of 3000 W.

1 answer:

maria [59]4 years ago

5 0

3kW X 0.5hours
= 1.5 kWh

You might be interested in

A 0.260 m radius, 525 turn coil is rotated one-fourth of a revolution in 4.17 ms, originally having its plane perpendicular to a

Sophie [7]

Answer:

B = 0.37T

Explanation:

In order to calculate the needed magnitude of the magnetic force you use the following formula, which calculate the induced emf of the solenoid when there is a change in the magnetic flux:

$emf=-N\frac{\Delta \Phi_B}{\Delta t}=-N\frac{\Delta (BAcos\theta)}{\Delta t}$ (1)

emf: induced voltage in the solenoid = 10,000V

N: turns of the solenoid = 525

ФB: magnetic flux

B: magnitude of the magnetic field = ?

A: cross-sectional area of the solenoid = π*r^2

r: radius of the cross-sectional area = 0.260m

Δt: interval time of the change of the magnetic flux = 4.17ms = 4.17*10^-3s

First, you have the magnetic field direction perpendicular to the plane of the solenoid, after, the angle between them is 90° (quarter of a revolution)

In the equation (1) the only parameter that changes on time is the angle, then, you can solve for B from the equation (1):

$emf=-NBA\frac{cos(90\°)-cos(0\°)}{\Delta t}=\frac{NBA}{\Delta t}\\\\B=\frac{(\Delta t)(emf)}{NA}=\frac{(\Delta t)(emf)}{N(\pi r^2)}\\\\$

Finally, you replace the values of the parameters to calculate B:

$B=\frac{(4.17*10^{-3}s)(10000V)}{(525)(\pi(0.260m)^2)}=0.37T$

The strength of the magnetic field is 0.37T

7 0

3 years ago

what are the 3 properties of components of the universe that can be determined using electromagnetic radiation?

stepan [7]

Your answer is electricity, light and magnetism. They can be determined usinf elecromagnetic radioation.
<span>
Even the energy can't be detected by our eyes, there are a lot of measurement instruments that can measure infrared (IR), gamma rays, radio or X-rays or ultraviolet (UV)</span>

4 0

3 years ago

The following three hot samples have the same temperature. The same amount of heat is removed from each sample. Which one experi

vlabodo [156]

Answer:

Smallest drop: Water

Largest drop: Dirt

Explanation:

The heat needed to change the temperature of a sample is:

$Q=cm\Delta T$ (1)

with Q the heat (added(+) or removed(-)), c specific heat, m the mass and $\Delta T$ the change in temperature of the sample. So, if we solve (1) for

Sample A:

$\Delta T=-\frac{Q}{cm} =\frac{Q}{4186*4.0}$

$\Delta T=-\frac{Q}{16744}$

Sample B:

$\Delta T=-\frac{Q}{cm} =\frac{Q}{2700*2.0}$

$\Delta T=-\frac{Q}{5400}$

Sample C:

$\Delta T=-\frac{Q}{cm} =\frac{Q}{1050*9.0}$

$\Delta T=-\frac{Q}{9450}$

Note that the numbers 16744, 5400, 9450 are in the denominator of the expression $-\frac{Q}{cm}$ that gives the drop on temperature. so, if Q is the same for the three samples the smallest denominator gives the largest drop and vice versa.

So, the smallest drop is Sample A and the largest is Sample C.

(Important: The minus sign of $\Delta T$ implies the temperature is dropping)

8 0

3 years ago

Robert is accelerating a cart at the rate of 2.2 meters/second2. If the mass in the cart is doubled, and the net force is also d

skad [1K]

F = ma
double f and m gives
(2f) = (2m)a
notice a is unchanged = 2.2
m/s^2

4 0

3 years ago

Read 2 more answers

The left fielder throws the baseball home from 60 m away. The ball's horizontal velocity is 30 m/s, and its vertical velocity is

Vikentia [17]

Answer:

The base runner

Explanation:

To know the correct answer to the question, we shall determine the time taken for the baseball and the base runner to get to the home plate. This is illustrated below:

For the baseball:

Horizontal velocity (u) = 30 m/s

Horizontal distance (s) = 60 m

Time (t) =?

s = ut

60 = 30 × t

Divide both side by 30

t = 60 / 30

t = 2 s

Thus, it will take the baseball 2 s to get to the home plate.

For the base runner:

Horizontal velocity (u) = 5 m/s

Horizontal distance (s) = 5 m

Time (t) =?

s = ut

5 = 5 × t

Divide both side by 5

t = 5 / 5

t = 1 s

Thus, it will take the base runner 1 s to get to the home plate.

SUMMARY:

Time taken for the baseball to get to the home plate = 2 s

Time taken for the base runner to get to the home plate = 1 s

From the calculations made above, we can conclude that the base runner will arrive at the home plate first because it took him 1 s to get to the home plate whereas the baseball took 2 s to get there.

7 0

3 years ago