Unlike mechanical waves such as sound or earthquake waves, EM waves can travel through empty space. True or false

A 39.5 kg child stands at the center of a 125 kg playground merry-go-round which rotates at 3.10 rad/s. If the child moves to th

Neporo4naja [7]

Using the law of conservation of angular momentum, we have

I1 w1 = I2 w2 

ie., m1r^2/2 x w1 = ( m1r^2/2 + m2r^2 ) w2 

ie., new angular velocity w2 = m1 w1 / ( m1+ 2m2) = 125 x 3.1 / ( 125 + 2 x39.5 ) 

= 1.8995 = 1.9 rad /sec ( nearly )

3 0

4 years ago

there is only one basic format for a professional report. a. audience b. All of these should be considered when deciding on a re

Anna007 [38]

Answer:

The answer is letter b. All of these should be considered when deciding on a report format.

Explanation:

A Professional Report is a type of formal document about a topic or information that is intended for a specific audience or purpose. The report's style of writing needs a lot of knowledge from the writer. Oftentimes, it involves the following important elements: Title, Summary, Body, Discussion, Conclusion and Recommendation.

The writer should write according to his target audience and purpose. He also needs to consider the length of his report, as well as the suitable words and sentences that he should use.

Thus, all of the choices are important in writing a professional report. So, the answer is letter b.

5 0

3 years ago

A plasma wave moving through a plasma has a frequency of 109 Hz and a speed of 3.0 × 107 m/s. What is the wavelength of this wav

tigry1 [53]

Answer:0.27*10^{6} (m)

Explanation:

with a wave we know that speed= wavelenght* frecuency so

wavelenght= 3*10^{7} / 109 = 0.27*10^{6} (m)

8 0

3 years ago

In each case, lifting or pushing, why must you exert a force to move the object? Q1-2: How much more effort is required to lift

musickatia [10]

Answer:

Newton's first law applies. An object at rest will stay that way until a force is applied.
Any amount of effort can be applied to any amount of mass (in the ideal case). The question is not sufficiently specific.

Explanation:

A force is required to move an object because the object will stay at rest until a force is applied.

__

The effort required to lift or push two masses instead of one depends on the desired effect. For the same kinetic energy, no more effort is required. For the same momentum, half the effort is required for two masses. For the same velocity, double the effort is required.

4 0

3 years ago

A rocket blasts off vertically from rest on the launch pad with an upward acceleration of 2.90 m/s2 . At 20.0s after blastoff, t

Brilliant_brown [7]

Answer:

A) 580m

B) 0 m/s

C) 9.8m/s^2

D) downward

E) 10.87s

F) 106.62 m/s

Explanation:

A) The distance traveled by the rocket is calculated by using the following expression:

$y=\frac{1}{2}at^2$

a: acceleration of the rocket = 2.90 m/s^2

t: time of the flight = 20.0 s

$y=\frac{1}{2}(2.90\frac{m}{s^2})(20.0s)^2=580m$

B) In the highest point the rocket has a velocity with magnitude zero v = 0m/s because there the rocket stops.

C) The engines of the rocket suddenly fails in the highest point. There, the acceleration of the rocket is due to the gravitational force, that is 9.8 m/s^2

D) The acceleration points downward

E) The time the rocket takes to return to the ground is given by:

$t=\sqrt{\frac{2y}{g}}=\sqrt{\frac{2(580m)}{9.8m/s^2}}=10.87s$

10.87 seconds

F) The velocity just before the rocket arrives to the ground is:

$v=\sqrt{2gy}=\sqrt{2(9.8m/s ^2)(580m)}=106.62\frac{m}{s}$

6 0

3 years ago