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trapecia [35]
3 years ago
10

A kettle is rated at 1 kW, 220 V. Calculate the working resistance of the kettle.

Physics
1 answer:
Anna [14]3 years ago
5 0

Explanation:

Power of electric kettle, P = 1 kW

Voltage, V = 220 V

(a) Electric power is given by the formula as follows :

P=\dfrac{V^2}{R}

R is resistance

R=\dfrac{V^2}{P}\\\\R=\dfrac{(220)^2}{10^3}\\\\R=48.4\ \Omega

(b) When connected to a 220 V supply, it takes 3 minutes for the water in the kettle to reach boiling point.

Energy supplied is given by :

E=P\times t

P is power, P=\dfrac{V^2}{R}

E=\dfrac{V^2}{R}t\\\\E=\dfrac{(220)^2}{48.4}\times 180\\\\E=180000\ J\\\\E=180\ kJ

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mario62 [17]

Velocity of vw bug is given as

v_1 = 54 mpH towards north

velocity of imphala is given as

v_2 = 47 mph towards south

now we need to find velocity of imphala relative to bug

v_{21} = v_2 - v_1

v_{21} = 47 - (-54) = 101 mpH

so the speed is 101 mpH towards south so correct option is C

5 0
3 years ago
Two workers are sliding 350 kgkg crate across the floor. One worker pushes forward on the crate with a force of 390 NN while the
svetoff [14.1K]

Answer:

\mu_k=0.18

Explanation:

First, we write the equations of motion for each axis. Since the crate is sliding with constant speed, its acceleration is zero. Then, we have:

x: T+F-f_k=0\\\\y:N-mg=0

Where T is the tension in the rope, F is the force exerted by the first worker, f_k is the frictional force, N is the normal force and mg is the weight of the crate.

Since f_k=\mu_k N and N=mg, we can rewrite the first equation as:

T+F-\mu_k mg=0

Now, we solve for \mu_k and calculate it:

\mu_k=\frac{T+F}{mg}\\ \\\mu_k =\frac{220N+390N}{(350kg)(9.8m/s^{2})} =0.18

This means that the crate's coefficient of kinetic friction on the floor is 0.18.

6 0
3 years ago
Describe how the three methods of thermal energy transfer may take place within the iguana’s enclosure.
sasho [114]

Answer:

Heat can travel from one place to another in three ways: Conduction, Convection and Radiation. Both conduction and convection require matter to transfer heat.  Conduction is the transfer of heat between substances that are in direct contact with each other. Thermal energy is transferred from hot places to cold places by convection. Radiation is a method of heat transfer that does not rely upon any contact between the heat source and the heated object as is the case with conduction and convection. Heat can be transmitted through empty space by thermal radiation often called infrared radiation.

Explanation:

6 0
3 years ago
Read 2 more answers
during convection, hot material _____ (expands & sinks, cools & rises, expands & rises, deflates & rises) then m
Lady bird [3.3K]

Answer:

During convection, hot material expands & rises then moves to the side and cools & sinks. this circular pattern is called a convection current.

Explanation:

Convection is one of the three methods of transfer of heat. It occurs only in fluids (liquids or gases).

Convection occurs when there is a source of heat that heats a fluid, such as in a boiling pot of water. The water which is on the bottom of the pot becomes warmer before than the water at the top (because it is closer to the flame), and so it becomes less dense: for this reason, it expands and it becomes rising. On the contrary, the water on top is colder, so it is more dense and starts sinking, replacing the warmer water. As the new part of water gets warmer, it starts rising, and so the process is continuously repeated. This circular current is called convection current.

4 0
3 years ago
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9- Under what circumstances would a vector have components that are equal in
valkas [14]

Explanation:

c. if the vector is oriented at 0° from the X -axis.

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