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3 years ago

In the figure above, a box of mass 2.5kg is initially at rest on a rough inclined plane. Assuming the

Physics

1 answer:

neonofarm [45]3 years ago

5 0

Answer:

Explanation:

By work - energy theorem on the box

Wmg + wn + wf = kf - ki

=> mgh + 0 + wf = 1/2 mv^2f - 1/2mv^2i

=> wf = 1/2mv^2f - 1/2mv^2i - mgh

:. Wf = 1/2×2.5×4^2 - 0- 2.5×9.8×1.5

= 20 - 36.75

= -16.75 J

Work done comes out negative here which is expected as the friction always act opposite to the velocity of an object. Friction is a non conservative force and it causes loss of mechanical energy.

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A 331 N stoplight is hanging in equilibrium from cables as shown. The tension in the right cable is 550 N, and it makes an angle

VARVARA [1.3K]

Let
F=tension of cable on the left
x=angle of left cable makes with the horizontal

Resolve forces vertically (y-direction)
331=550sin(12)+Fsin(x) =>
Fsin(x)=331-550sin(12)=216.649..........(1)

Resolve forces horizontally (x-direction)
Fcos(x)=550cos(12) =>
Fcos(x)=537.981............................(2)

Divide (1) by (2)
tan(x)=Fsin(x)/Fcos(x)=0.40271
x=atan(0.40271) = 21.935 °

From (2),
F=537.981/cos(x)=537.981/0.92761 = 579.965 N

Check:
Fsin(x)+550sin(12)=579.965*sin(21.935)+550*sin(12) = 331.000 ok
Fcos(x)=537.981
550sin(12)=537.981 ok

8 0

3 years ago

Why must indirect evidence be used to study the structure of atoms?

Sloan [31]

Indirect evidence must be used to study the structure of atoms, because the direct evidence affects the position and energy of the particles of the atomic structure.

For example, imagine you use a light ray to find the location of an electron in an atomic structure, the current location of the electron you are now seeing is as a result of the light ray, and the electron has changed it's initial position to a new position as a result of the effect of the light ray.

So indirect means would probably give more accurate answers about the atomic structure than that of the direct means.

An example of the indirect means would be for example setting up a mathematical equation or model of the atomic structure and trying to provide solution for the model or equation.

8 0

3 years ago

A 90 kg painter is standing on a horizontal wooden scaffolding of length 10 m, which is supported on each end by a rope. The pai

RSB [31]

Explanation:

For equilibrium, $\sum M = 0$ .

So, $8 m \times mg - (10 m) T_{1}$ = 0

$T_{1} = \frac{8 \times mg}{10}$

= $\frac{8 \times 90 \times 9.8}{10}$

= 705.6 N

Also, for equilibrium $\sum F_{y}$ = 0

$T_{1} + T_{2} - mg$ = 0

or, $T_{2} = mg - T_{1}$

= $90 \times 9.8 - 705.6$

= 176.4 N

Thus, we can conclude that the tension in the first rope is 176.4 N.

8 0

3 years ago

Calculate the wavelength of a photon having 3.26 x 10^-19 joules of energy

bekas [8.4K]

The energy of a photon is given by:
$E=hf$
where h is the Planck constant and f is the photon frequency.
We know the energy of the photon, $E=3.26 \cdot 10^{-19} J$ , so we can rearrange the equation to calculate the frequency of the photon:
$f= \frac{E}{h}= \frac{3.26 \cdot 10^{-19}J}{6.6 \cdot 10^{-34}Js}=4.94 \cdot 10^{14}Hz$

And now we can use the following relationship between frequency f, wavelength $\lambda$ and speed of light c to find the wavelength of the photon:
$\lambda= \frac{c}{f}= \frac{3 \cdot 10^8 m/s}{4.94 \cdot 10^{14} Hz}=6.07\cdot 10^{-7} m=607 nm$

8 0

3 years ago

Where is the resistor located on the diagram?

Andrej [43]

The answer is B hope this helps

5 0

3 years ago

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