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2 years ago

Statements best explains why a scientific theory can be revised?

1 answer:

4 0

Answer: Because new theories can come out that better explain observations and experimental results can replace old theories.

Explanation: Theories more than ten years old are usually out of date. Scientists want to prove that the work of other scientists is wrong. New evidence that supports a change prompts scientists to modify earlier theories.

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A 1.2 kg block of wood hangs motionless from strings. A 50 gram bullet, traveling horzontally, strikes the block and becomes emb

Firdavs [7]

Answer:

speed of the bullet before it hit the block is 200 m/s

Explanation:

given data

mass of block m1 = 1.2 kg

mass of bullet m2 = 50 gram = 0.05 kg

combine speed V= 8.0 m/s

to find out

speed of the bullet before it hit the block

solution

we will apply here conservation of momentum that is

m1 × v1 + m2 × v2 = M × V .............1

here m1 is mass of block and m2 is mass of bullet and v1 is initial speed of block i.e 0 and v2 is initial speed of bullet and M is combine mass of block and bullet and V is combine speed of block and bullet

put all value in equation 1

m1 × v1 + m2 × v2 = M × V

1.2 × 0 + 0.05 × v2 = ( 1.2 + 0.05 ) × 8

solve it we get

v2 = 200 m/s

so speed of the bullet before it hit the block is 200 m/s

8 0

3 years ago

How can the IMA of a first- class lever be increased?

Dimas [21]

IMA = Ideal Mechanical Advantage

First class lever = > F1 * x2 = F2 * x1

Where F1 is the force applied to beat F2. The distance from F1 and the pivot is x1 and the distance from F2 and the pivot is x2

=> F1/F2 = x1 /x2

IMA = F1/F2 = x1/x2

Now you can see the effects of changing F1, F2, x1 and x2.

If you decrease the lengt X1 between the applied effort (F1) and the pivot, IMA decreases.

If you increase the length X1 between the applied effort (F1) and the pivot, IMA increases.

If you decrease the applied effort (F1) and increase the distance between it and the pivot (X1) the new IMA may incrase or decrase depending on the ratio of the changes.

If you decrease the applied effort (F1) and decrease the distance between it and the pivot (X1) IMA will decrease.

Answer: Increase the length between the applied effort and the pivot.

4 0

3 years ago

Read 2 more answers

From the concepts you have learned in this module, how are you going to assess

Daniel [21]

Answer:

Find the explanation below.

Explanation:

Earth is properly designed to support life. This is seen in the favorable temperature that supports life, the water cycle that recycles water for plant and animal life, the atmosphere, energy, and nutrients.

1. Temperature: The temperature which is regulated by the different weather conditions such as the rains, snows, dry seasons all help to maintain a stable condition for life.

2. Water: The water cycle through processes like evaporation, condensation, precipitation, helps to ensure that there is never a lack of water in the earth. The numerous water bodies like the seas, oceans, rivers, lakes, also provide a habitat for some living things. Water makes up 70% of the earth.

3. Atmosphere: The atmosphere is a mixture of gases in the right proportions that are necessary for life. Oxygen, Nitrogen, Carbon, etc are released and inhaled by man and other living things. They are also involved in so many biochemical reactions that help in metabolism and catabolism.

4. Energy: Energy generated from the sun and within the earth is stored in various forms and is always conserved. This energy is converted to different states such as the potential, chemical, kinetic, mechanical forms to get work done and to release heat.

5. Nutrients: Though cycles such as the carbon, nitrogen, oxygen, and phosphorous cycles, the earth maintains its stock of essential nutrients that help to sustain life.

6 0

4 years ago

Radar uses radio waves of a wavelength of 2.4 ${\rm m}$ . The time interval for one radiation pulse is 100 times larger than t

blondinia [14]

Answer:

120 m

Explanation:

Given:

wavelength 'λ' = 2.4m

pulse width 'τ'= 100T ('T' is the time of one oscillation)

The below inequality express the range of distances to an object that radar can detect

τc/2 < x < Tc/2 ---->eq(1)

Where, τc/2 is the shortest distance

First we'll calculate Frequency 'f' in order to determine time of one oscillation 'T'

f = c/λ (c= speed of light i.e 3 x $10^{8}$ m/s)

f= 3 x $10^{8}$ / 2.4

f=1.25 x $10^{8}$ hz.

As, T= 1/f

time of one oscillation T= 1/1.25 x $10^{8}$

T= 8 x $10^{-9}$ s

It was given that pulse width 'τ'= 100T

τ= 100 x 8 x $10^{-9}$ => 800 x $10^{-9}$ s

From eq(1), we can conclude that the shortest distance to an object that this radar can detect:

$x_{min}$ = τc/2 => (800 x $10^{-9}$ x 3 x $10^{8}$ )/2

$x_{min}$ =120m

8 0

3 years ago

The same wave travels for 2 seconds, what is its frequency?*

sveticcg [70]

Answer:

In waves distance is measured by wave length and time is measured by frequency or period.

velocity ratio=wave length multiply by frequency.

HENCE, if the same wave travels for 2 econds its frequency will be 2Hz.

Explanation:

8 0

3 years ago