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3 years ago

What does a battery powered heater warms up from ?

Physics

1 answer:

Westkost [7]3 years ago

8 0

Battery based heaters use electric resistance heating, which uses a lot of current (electricity) to create the heat.

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A girl launches a toy rocket from the ground. The engine experiences an average thrust of 5.26 N. The mass of the engine plus fu

Triss [41]

Answer: The answer for A is - v = 786.93 m/s

The answer for B is - v = 122.40 m/s

Explanation:

a) To find the average exhaust speed (v) of the engine we can use the following equation:

F = vΔm

Where:

F: is the thrust by the engine = 5.26 N

Δm: is the mass of the fuel = 12.7 g

Δt: is the time of the burning of fuel = 1.90 s

v = F×ΔT/ΔT

b) To calculate the final velocity of the rocket we need to find the acceleration.

The acceleration (a) can be calculated as follows:

a = F/M

In the above equation, m is an average between the mass of the engine plus the rocket case mass and the mass of the engine plus the rocket case minus the fuel mass:

m = (m_{engine} + m_{rocket}) + (m_{engine} + m_{rocket} - m_{fuel})}{2} = {2*m_{engine} + 2*m_{rocket} - m_{fuel}}{2} = 2*25.0 g + 2*63.0 g - 12.7 g}{2} = 81.65 g

Now, the acceleration is:

a = 5.26 N/81.65-t 10^³kg} = 64.42 m*s^²

Finally, the final velocity of the rocket can be calculated using the following kinematic equation:

v= v_{0} + at = 0 + 64.42 m*s^{-2}*1.90 s = 122.40 m/s

7 0

3 years ago

Two 75 W (120 V) lightbulbs are wired in series, then the combination is connected to a 120 V supply. Part A How much power is d

Elenna [48]

Answer:

300 W

Explanation:

power of each bulb P = 75 W

voltage in the circuit = 120 V

we know that electrical power P = IV ....1

and V = IR

we can also say that I = V/R

substituting for I in equation 1, we have

P = $V^{2}/R$ ....2

The total total power in the circuit = 75 x 2 = 150 W

from equation 2, we have

150 = $120^{2} /R$

R = $120^{2}/150$ = 96 Ω this is the resistance of the whole circuit.

This resistance is due to the two light bulbs, for each light bulb since they are arranged in series

R = 96/2 = 48 Ω

From P = $V^{2}/R$

for each light bulb, power is

P = $120^{2} /48$ = 300 W

8 0

3 years ago

A cathode ray tube is made of glass with a small amount of some kind of gas in it. It has metal electrodes at each end to pick u

LuckyWell [14K]

Scientists could investigate this idea by making cathode ray tubes out of different materials to see if the ray was the same.

6 0

3 years ago

Read 2 more answers

Collision practice

NikAS [45]

Answer:

$v_f=4\:\mathrm{m/s\: in\:Biff's\:direction}$

Explanation:

Using the Law of Conservation of Momentum, we can set up the following equation:

$m_2v_2-m_1v_1=m_fv_f$ , where $m_1v_1$ is Bruce's momentum and $m_2v_2$ .

Plugging in given values, we get:

$90\cdot7-45\cdot2=(90+45)v_f, \\v_f=\frac{540}{135}=\fbox{$4\:\mathrm{m/s}$}$ .

6 0

3 years ago

An ice-skater is moving at a constant velocity across an icy pond, The skater throws a snowball directly ahead.

Murljashka [212]

Answer:

(D) It is equal to the original velocity of the skater.

Explanation:

The velocity of the center of mass of a system is

$\vec{v}_{cm} = \frac{m1\vec{v}_1 + m_2\vec{v}_2}{m_1 + m_2}$

The velocity of the center of mass is constant if there is no external force, because the total momentum of the whole system is conserved.

So, before the snowball is thrown, the velocity of the center of mass is equal to that of the skater. This velocity will always be equal to the velocity of the center of mass of the system.

6 0

4 years ago