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3 years ago

1. What is the relationship between wavelength and the penetrating power of an electromagnetic wave?

Physics

1 answer:

Andreyy893 years ago

6 0

As we know that energy of electromagnetic wave is given by

$E = \frac{hc}{\lambda}$

so here we know that penetrating power will directly depends on its energy and energy inversely depends on wavelength

So here we can say correct answer will be

C) The penetrating power decreases as the wavelength increases.

Speed of sound is maximum in solids and minimum in gas

so here as ice melts into water the speed of sound must have to decrease

so correct answer will be

D) The speed of sound would decrease because sound travels faster through solids than liquids.

mechanical waves required medium to travel while non mechanical waves do not require any medium to travel

so here correct answer will be

A) sound

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Zak, helping his mother rearrange the furniture in their living room, moves a 60 kg sofa 5.9 m with a constant force of 40 N. Wh

Len [333]

Answer:236 J

Explanation:

Given

Mass of sofa $m=60 kg$

Displacement $s=5.9 m$

Force $F=40 N$

neglecting Friction

Work done is given by

$W=F\cdot s$

$W=F\cdot s\cos 0$

$W=40\cdot 5.9$

$W=236 J$

4 0

3 years ago

Read 2 more answers

The two blocks in oscillate on a frictionless surface with a period of 1.5 s. The upper block just begins to slip when the ampli

Setler79 [48]

Answer:

0.72

Explanation:

$T$ = Time period of oscillation = 1.5 s

Angular frequency is given as

$w = \frac{2\pi }{T}\\w = \frac{2(3.14) }{1.5}\\w = 4.2 rad/s$

$A$ = Amplitude of oscillation = 40 cm = 0.40 m

$\mu$ = Coefficient of static friction = ?

$a$ = acceleration of the block

$m$ = mass of the block

Maximum acceleration of the block is given as

$a = Aw^{2}$

frictional force is given as

$f = \mu mg$

As per newton's second law

$f = ma \\\\\mu mg = ma \\\mu g = a\\\mu g = Aw^{2}\\\mu (9.8) = (0.40)(4.2)^{2}\\\mu = 0.72$

8 0

3 years ago

The hot glowing surfaces of stars emit energy in the form of electromagnetic radiation. It is a good approximation to assume tha

belka [17]

Given that,

Energy $H=2.7\times10^{31}\ W$

Surface temperature = 11000 K

Emissivity e =1

(a). We need to calculate the radius of the star

Using formula of energy

$H=Ae\sigma T^4$

$A=\dfrac{H}{e\sigma T^4}$

$4\pi R^2=\dfrac{H}{e\sigma T^4}$

$R^2=\dfrac{H}{e\sigma T^4\times4\pi}$

Put the value into the formula

$R=\sqrt{\dfrac{2.7\times10^{31}}{1\times5.67\times10^{-8}\times(11000)^4\times 4\pi}}$

$R=5.0\times10^{10}\ m$

(b). Given that,

Radiates energy $H=2.1\times10^{23}\ W$

Temperature T = 10000 K

We need to calculate the radius of the star

Using formula of radius

$R^2=\dfrac{H}{e\sigma T^4\times4\pi}$

Put the value into the formula

$R=\sqrt{\dfrac{2.1\times10^{23}}{1\times5.67\times10^{-8}\times(10000)^4\times4\pi}}$

$R=5.42\times10^{6}\ m$

Hence, (a). The radius of the star is $5.0\times10^{10}\ m$

(b). The radius of the star is $5.42\times10^{6}\ m$

8 0

3 years ago

In which of the following cases will the normal force on a box be the greatest? A. When the box is placed in a stationary elevat

Butoxors [25]

Answer:

D. When the box is placed in an elevator accelerating upward

Explanation:

Looking at the answer choices, we know that we want to find out how the normal force varies with the motion of the box. In all cases listed in the answer choices, there are two forces acting on the box: the normal force and the force of gravity. These two act in opposite directions: the normal force, N, in the upward direction and gravity, mg, in the downward direction. Taking the upward direction to be positive, we can express the net force on the box as N - mg.

From Newton's Second Law, this is also equal to ma, where a is the acceleration of the box (again with the upward direction being positive). For answer choices (A) and (B), the net acceleration of the box is zero, so N = mg. We can see how the acceleration of the elevator (and, hence, of the box) affects the normal force. The larger the acceleration (in the positive, i.e., upward, direction), the larger the normal force is to preserve the equality: N - mg = ma, N = ma+ mg. Answer choice (D), in which the elevator is accelerating upward, results in the greatest normal force, since in that case the magnitude of the normal force is greater than gravity by the amount ma.

4 0

3 years ago

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A boy holds a heavy package for one hour. He is very tired but has not done any work. Explain why he did not do any work.

Feliz [49]

Answer:he's not applying force or motion

Explanation:

p=f & m

5 0

2 years ago