1. My grass is dying, and I believe it's because it is not getting enough water. Sol

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

Andreyy89

#1

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.

#2

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.

#3

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

6 0

3 years ago

1. A carbon atom contains 6 protons and 6 electrons. In order for the carbon atom to become

jek_recluse [69]

It must gain an electron because if the proton number was to change it would no longer be the same element.

5 0

3 years ago

A cord is used to vertically lower an initially stationary block of mass M = 3.6 kg at a constant downward acceleration of g/7.

dalvyx [7]

Answer:

(a) $W_c=127.008 J$

(b) $W_g=148.176 J$

(c) K.E. = 21.168 J

(d) $v=3.4293m.s^{-1}$

Explanation:

Given:

mass of a block, M = 3.6 kg

initial velocity of the block, $u=0 m.s^{-1}$

constant downward acceleration, $a_d= \frac{g}{7}$

$\Rightarrow$ That a constant upward acceleration of $\frac{6g}{7}$ is applied in the presence of gravity.

∴ $a=- \frac{6g}{7}$

height through which the block falls, d = 4.2 m

(a)

Force by the cord on the block,

$F_c= M\times a$

$F_c=3.6\times (-6)\times\frac{9.8}{7}$

$F_c=-30.24 N$

∴Work by the cord on the block,

$W_c= F_c\times d$

$W_c= -30.24\times 4.2$

We take -ve sign because the direction of force and the displacement are opposite to each other.

$W_c=-127.008 J$

(b)

Force on the block due to gravity:

$F_g= M.g$

∵the gravity is naturally a constant and we cannot change it

$F_g=3.6\times 9.8$

$F_g=35.28 N$

∴Work by the gravity on the block,

$W_g=F_g\times d$

$W_g=35.28\times 4.2$

$W_g=148.176 J$

(c)

Kinetic energy of the block will be equal to the net work done i.e. sum of the two works.

mathematically:

$K.E.= W_g+W_c$

$K.E.=148.176-127.008$

K.E. = 21.168 J

(d)

From the equation of motion:

$v^2=u^2+2a_d\times d$

putting the respective values:

$v=\sqrt{0^2+2\times \frac{9.8}{7}\times 4.2 }$

$v=3.4293m.s^{-1}$ is the speed when the block has fallen 4.2 meters.

6 0

3 years ago

A 1980-kg car is traveling with a speed of 15.5 m/s. What is the magnitude of the horizontal net force that is required to bring

Dennis_Churaev [7]

Answer: 6067.5 N

Explanation:

Work = Change in Energy. To start, all of the energy is kinetic energy, so find the total KE using: KE = 1/2(m)(v^2). Plug in 1980 kg for m and 15.5 m/s for v and get KE = 237847.5 J.

Now, plug this in for work: Work = Force * Distance; so, divide work by distance to get 6067.5 N.

5 0

2 years ago

Your laundry basket weighs 22 N and your room is 3.0 m above you on the second floor. It takes you 6.0 seconds to carry the laun

Fofino [41]

<h2>Power is 11 W</h2>

Explanation:

Power = Work ÷ Time

Work = Force x Displacement

Force = 22 N

Displacement = 3 m

Time = 6 seconds

Substituting

Work = Force x Displacement

Work = 22 x 3 = 66 J

Power = Work ÷ Time

Power = 66 ÷ 6

Power = 11 W

Power is 11 W

8 0

3 years ago