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3 years ago

Need help on 21 will give brainliest

Physics

2 answers:

elena55 [62]3 years ago

8 0

You forgot To post a picture of The question

natulia [17]3 years ago

5 0

The answer to question 21 is ~insert answer here~

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A block with a weight of 3.0 N is at rest on a horizontal surface.A 1.0 N upward force is applied to the block by means of an at

Genrish500 [490]

Answer:

Explanation:

Given

weight of block $W=3\ N$

A force is of $F=1 N$ is applied on the block

As 1 N is less than weight of block so block exert Force less than its weight

$F_{net}=mg-F$

$F_{net}=3-1=2\ N$

So Block exert a force of 2 N downward on floor

8 0

4 years ago

A rock climber wears a 8.1 kg backpack while scaling a cliff. After 28.2 min, the climber is 9.4 m above the starting point. How

mart [117]

Answer:

Explanation:

mass of backpack, m = 8.1 kg

weight of climber, W = 656 N

height raised, h = 9.4 m

time, t = 28.2 min = 28.2 x 60 = 1692 second

weight of backpack, w = m x g = 8.1 x 9.8 = 79.38 N

Work done by the climber on the backpack = mg x h = 79.38 x 9.4 = 746.17 J

Wok done in lifting herself + backpack = (W + w) x h

= (656 + 79.38) x 9.4 = 6912.57 J

Power developed by the climber,P = Total work / time

P = 6912.57 / 1692 = 4.09 W

3 0

4 years ago

What is the internal energy of 3.00 mol of N2 gas at 25 degrees C? To solve this problem, use the equation: U electronic gas = 5

allochka39001 [22]

Given data

Determine Internal energy of gas N₂, (U) = ?

Temperature (T) = 25° C

= 25+273 = 298 K,

Gas constant (R) = 8.31 J/ mol-K ,

Number of moles (n) = 3 moles,

Internal energy of N₂

Internal energy is a property of thermodynamics, the concept of internal energy can be understand by ideal gas. For example N₂, the observations for oxygen and nitrogen at atmospheric temperatures, f=5, (where f is translational degrees of freedom).

So per kilogram of gas,

The internal energy (U) = 5/2 .n.R.T

= (5/2) × 3 × 8.31 ×298

= 18572.85 J

The internal energy of the N₂ is 18,572.85 J and it is approximately equal to 18,600 J given in the option B.

8 0

3 years ago

Read 2 more answers

The lights used by Mark Watley (played by Matt Damon) during the film The Martian seem to be Metal Halide lamps. Metal Halide la

dimaraw [331]

Answer:

According to the answer, the speed of light is being achieved.

Explanation:

The velocity of the light is:

$C=\frac{E}{P}$

Where E = energy = 3.03x10⁻¹⁹J

P = momentum = 1.01x10⁻²⁷kgm/s

Replacing:

$C=\frac{3.03x10^{-19} }{1.01x10^{-27} } =3x10^{8} m/s$

5 0

3 years ago

What minimum speed must an electron have to excite the 492-nm-wavelength blue emission line in the hg spectrum?

mezya [45]

The energy required by the excitation of the line is:
ΔE = hν = hc / λ
where:
ΔE = energy difference
h = Planck constant
ν = line frequency
c = speed of light
λ = line wavelength

The energy difference must be supplied by the electron, supposing it transfers all its kinetic energy to excite the line:
$\Delta E = \frac{1}{2} m v^{2}$

Therefore,
$\frac{1}{2} m v^{2} = \frac{hc}{\lambda}$

And solving for v we get:
$v = \sqrt{ \frac{2hc}{m\lambda} }$

Plugging in numbers (after trasforing into the correct SI units of measurement):
$v = \sqrt{ \frac{(2)(6.6 \cdot 10^{-34})(3 \cdot 10^{8}) }{(9.11 \cdot 10^{-31})(4.92 \cdot 10^{-7}) } }$
=9.4 · 10⁵ m/s

Hence, the electron must have a speed of 9.4 · 10⁵ m/s in order to excite the 492nm line.

5 0

3 years ago