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3 years ago

Which best describes the history of scientific knowledge?

1 answer:

8 0

A path of inferences guided to be cherry picked as for which ones were reasonable and which ones had no ability in the real world to sustain in scientific law

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A student looks at ocean waves coming into the beach. An ocean wave with more energy will A) have a greater height. B) have a gr

attashe74 [19]

It would be A: Have a greater height.

The higher the wave the higher the energy!

3 0

2 years ago

Read 2 more answers

A 65kg person throws a 0.045kg snowball forward with a ground speed of 30m/s. A second person, with a mass of 60kg, catches the

asambeis [7]

Answer:

v₁ = 2.48m/s, v₂ = 0.02m/s

Explanation:

Momentum p must be conserved. p = mv

1) First person throwing the snow ball. The momentum before the throw:

p = (65kg + 0.045kg) * 2.5 m/s

The momentum after the throw:

p = 65kg * v₁ + 0.045kg * 30m/s

Solving for the velocity v₁ of person 1:

v₁ = ((65kg + 0.045kg) * 2.5 m/s - 0.045kg * 30m/s) / 65kg = 2.48m/s

2) Second person catching the ball. The momentum before the catch:

p = 0.045kg * 30m/s + 60kg * 0m/s

The momentum after the catch:

p = (60kg + 0.045kg) * v₂

Solving for velocity v₂ of person 2:

v₂ = 0.045kg * 30m/s / (60kg + 0.045kg) = 0.02 m/s

5 0

3 years ago

A pulley with a mechanical advantage of 5 will require you to pull _____ times the amount of rope.

Marat540 [252]

Answer:

It will require a force of 1/5, answer A.

Explanation:

In the attached image we can see an example of an array of pulleys that will lift a 100 kg-f load.

If we analyze pulleys A,B, and C as in the image we can check a force in the cable of 20kg-f.

In the pulley D we have three forces of 20 kg-f each and those forces plus the forces in the pulley B, sum a total of 100 kg-f (60+40). This matches the mechanical advantage (100/5) = 20 kg-f

6 0

2 years ago

How much time does it take for a car travelling at 5m/s in 21 metres

Paha777 [63]

Answer:

21/5 seconds or 4.2 seconds

Explanation:

Distance=Speed*Time

21=5 *Time

21/5=Time

4.2=time

7 0

3 years ago

Read 2 more answers

What is the requirement for the photoelectric effect? Select one: a. The incident light must have enough intensity b. The incide

Softa [21]

Answer:

c. The incident light must have at least as much energy as the electron work function

Explanation:

In photoelectric effect, electrons are emitted from a metal surface when a light ray or photon strikes it. An electron either absorbs one whole photon or it absorbs none. After absorbing a photon, an electron either leaves the surface of metal or dissipate its energy within the metal in such a short time interval that it has almost no chance to absorb a second photon. An increase in intensity of light source simply increase the number of photons and thus, the number of electrons, but the energy of electron remains same. However, increase in frequency of light increases the energy of photons and hence, the

energy of electrons too.

Therefore, the energy of photon decides whether the electron shall be emitted or not. The minimum energy required to eject an electron from the metal surface, i.e. to overcome the binding force of the nucleus is called ‘Work Function’

Hence, the correct option is:

<u>c. The incident light must have at least as much energy as the electron work function</u>

3 0

2 years ago