How is this please help me

A 50-ω resistor is connected to a 9.0 V battery. How much thermal energy is produced in 7.5 minutes?1.2 * 10^2 J1.3 * 10^3 J3.0

emmasim [6.3K]

In order to calculate the thermal energy, first let's calculate the power, using the formula:

$P=\frac{V^2}{R}$

For a voltage V = 9 Volts and a resistance R = 50 ohms, we have:

$\begin{gathered} P=\frac{9^2}{50} \\ P=\frac{81}{50}=1.62\text{ W} \end{gathered}$

Now, multiplying the power by the time (in seconds), we can find the energy:

$\begin{gathered} E=P\cdot t \\ E=1.62\cdot7.5\cdot60 \\ E=729\text{ J} \end{gathered}$

In scientific notation, we have an energy of 7.3 * 10^2 J, therefore the correct option is the fourth one.

4 0

1 year ago

A wave With wavelength 20 m has a frequency of 12 Hz what is the waves speed

pentagon [3]

Answer:

240m/s

Explanation:

The equation to calculate is wavelength= velocity/ frequency so to find the velocity you would have to multiply frequency by wavelength.

7 0

3 years ago

A 20-kilogram child is riding on a 10-kg sled over a frictionless icy surface at 8.0 meters per second. Calculate the kinetic en

Veseljchak [2.6K]

Answer:

K = 960 J

Explanation:

Given that,

Mass of a child = 20 kg

Mass of a sled = 10 kg

Speed of child on sled = 8 m/s

We need to find the kinetic energy of the sled with the child.

The total mass of child and the sled = 20 kg + 10 kg

= 30 kg

The formula for the kinetic energy of an object is given by :

$K=\dfrac{1}{2}mv^2\\\\K=\dfrac{1}{2}\times 30\times (8)^2\\\\K=960\ J$

Hence, the kinetic energy of the sled with the child is 960 J.

6 0

3 years ago

A car travels from point A to point B, moving in the same direction but with a non-constant speed. The first half of the distanc

Dmitrij [34]

Answer:

Explanation:

From A to B

distance traveled with velocity $v_1$ in time $t_1$

$\frac{d}{2}=v_1t_1----1$

from B to C

distance traveled is 0.5 d with $v_2$ and $v_3$ velocity for half-half time

$\frac{d}{2}=\frac{v_2t_2}{2}+\frac{v_3t_3}{2}----2$

divide 1 and 2 we get

$\frac{1}{1}=\frac{2v_1t_1}{v_2t_2+v_3t_3}$

$\frac{t_1}{t_2}=\frac{v_2+v_3}{2v_1}$

Now average velocity is given by

$v_{avg}=\frac{d}{t_1+t_2}$

taking $t_1$ common

$v_{avg}=\frac{2v_1t_1}{t_1(1+\frac{t_2}{t_1})}$

$v_{avg}=\frac{2v_1}{1+\frac{2v_1}{v_2+v_3}}$

$v_{avg}=\frac{2v_1(v_2+v_3)}{2v_1+v_2+v_3}$

6 0

3 years ago

¿Cuál de las siguientes magnitudes es derivada?

Sedaia [141]

Answer:

A. El volumen

B. La densidad.

Explanation:

A derived quantity is defined as one that has to be calculated by using two or more other measurements.

Volume is a derived quantity because it requires one to use different measurements to determine it. For instance, in the case of a cube, the length, width and height of the cube are all needed to calculate volume.

Density is also a derived quantity because it needs both volume and mass for it to be calculated.

8 0

3 years ago

How is this please help me​

How is this please help me