Plz help.me woth these three questions asap

I’m not sure how to solve this

spayn [35]

Answer:

Option 10. 169.118 J/KgºC

Explanation:

From the question given above, the following data were obtained:

Change in temperature (ΔT) = 20 °C

Heat (Q) absorbed = 1.61 KJ

Mass of metal bar = 476 g

Specific heat capacity (C) of metal bar =?

Next, we shall convert 1.61 KJ to joule (J). This can be obtained as follow:

1 kJ = 1000 J

Therefore,

1.61 KJ = 1.61 KJ × 1000 J / 1 kJ

1.61 KJ = 1610 J

Next, we shall convert 476 g to Kg. This can be obtained as follow:

1000 g = 1 Kg

Therefore,

476 g = 476 g × 1 Kg / 1000 g

476 g = 0.476 Kg

Finally, we shall determine the specific heat capacity of the metal bar. This can be obtained as follow:

Change in temperature (ΔT) = 20 °C

Heat (Q) absorbed = 1610 J

Mass of metal bar = 0.476 Kg

Specific heat capacity (C) of metal bar =?

Q = MCΔT

1610 = 0.476 × C × 20

1610 = 9.52 × C

Divide both side by 9.52

C = 1610 / 9.52

C = 169.118 J/KgºC

Thus, the specific heat capacity of the metal bar is 169.118 J/KgºC

6 0

3 years ago

A person in bare feet is standing under a tree during a thunderstorm, seeking shelter from the rain. A lightning strike hits the

Anni [7]

Answer:

$I=38.181\ A$ is the current through the body of the man.

$E=34.5\ J$ energy dissipated.

Explanation:

Given:

time for which the current lasted, $t=43\times 10^{-6}\ s$

potential difference between the feet, $V=21000\ V$

resistance between the feet, $R=550\ \Omega$

$I=\frac{V}{R}$

$I=\frac{21000}{550}$

$I=38.181\ A$ is the current through the body of the man.

<u>Energy dissipated in the body:</u>

$E=I^2.R.t$

$E=38.181^2\times 550\times 43\times 10^{-6}$

$E=34.5\ J$

5 0

3 years ago

5. A construction worker on a high-rise building is on a platform suspended between two cables as illustrated below. The constru

Natalka [10]

Answer:

a) Tc = 750 [N] ;b) See the explanation below.

Explanation:

To solve this problem, we first need a graphical explanation of this, as well as knowing the corresponding questions. Therefore, a search was carried out in google, in the attached image we will find a graphical description of the problem.

b)

The solution of this type of problem corresponds to the use of Newton's third law, applying static which tells us that the sum of the forces in a system in equilibrium without movement must be equal to zero.

a)

In this way we can find by means of a sum of forces on the y axis equal to zero:

- 850 - 450 + 550 + Tc = 0

Tc = 750 [N]

4 0

3 years ago

You need to know the height of a tower, but darkness obscures the ceiling. You note that a pendulum extending from the ceiling a

Sonja [21]

Answer:

L=55.9m

Explanation:

The equation for the period of a simple pendulum is:

$T=2\pi\sqrt{\frac{L}{g}}$

In our case what we know is the period and the acceleration of gravity, and we need to know the length of the pendulum, so we can write:

$L=(\frac{T}{2\pi})^2g$

Which for our values is:

$L=(\frac{15s}{2\pi})^2(9.81m/s^2)=55.9m$

6 0

3 years ago

Plane-polarized light is incident on a single polarizing disk, with the direction of E0 parallel to the direction of the transmi

Vladimir [108]

Answer: $65.9^{\circ}$

Explanation:

Given

Intensity must be reduced by a factor of 6

Intensity is given by $I=I_o\cos ^2\theta\\$

Substitute $I$ by $\frac{I_o}{6}$

$\Rightarrow \dfrac{I_o}{6}=I_o\cos ^2\theta\\\\\Rightarrow \cos^2\theta =\dfrac{1}{6}\\\\\Rightarrow \cos \theta=\dfrac{1}{\sqrt{6}}\\\\\Rightarrow \theta=65.9^{\circ}$

So, the disk must be rotated by an angle of $65.9^{\circ}$ .

7 0

3 years ago