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soldier1979 [14.2K]
3 years ago
9

A student conducted an experiment that used two rose plants to determine if a liquid formula for fertilizer was better than a dr

y formula. He tested each fertilizer on a single plant for one month, and he concluded that the liquid formula was better. When he described his conclusion to his teacher, she told him he needed to conduct additional trials. The teacher most likely asked for additional trials because A.she did not believe the new formula helped plants grow better than the old formula. B.it was necessary to see data from more plants before the conclusion could be accepted. C.it was necessary to have tested the fertilizer on different kinds of plants. D.she thought he should test additional fertilizer formulas on the same two plants.
Physics
1 answer:
Serga [27]3 years ago
4 0
B. it was necessary to see data from more plants before the conclusion could be accepted.
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True or false. Students with a Learners License may not receive a motorcycle endorsement.
viktelen [127]
This is a true statement 
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3 years ago
15.<br> What can you do at school to help conserve the resources of the environment?
Alborosie

Answer: #1. Close the door when air conditioner is on  #2. I would use only 1 paper towel when drying your hands #3.  Recycle  #4. use water bottles that are not to be plastic.

<em>So these are things that you can do to conserve the resources from the environment in your school! </em> So hopefully i had helped you answer this question! Have a Great Day!

3 0
4 years ago
A quarterback passes a football from height h = 2.1 m above the field, with initial velocity v0 = 13.5 m/s at an angle θ = 32° a
alisha [4.7K]

Answer:

a)    x = v₀² sin 2θ / g

b)    t_total = 2 v₀ sin θ / g

c)    x = 16.7 m

Explanation:

This is a projectile launching exercise, let's use trigonometry to find the components of the initial velocity

        sin θ = v_{oy} / vo

        cos θ = v₀ₓ / vo

         v_{oy} = v_{o} sin θ

         v₀ₓ = v₀ cos θ

         v_{oy} = 13.5 sin 32 = 7.15 m / s

         v₀ₓ = 13.5 cos 32 = 11.45 m / s

a) In the x axis there is no acceleration so the velocity is constant

         v₀ₓ = x / t

          x = v₀ₓ t

the time the ball is in the air is twice the time to reach the maximum height, where the vertical speed is zero

          v_{y} = v_{oy} - gt

          0 = v₀ sin θ - gt

          t = v_{o} sin θ / g

         

we substitute

       x = v₀ cos θ (2 v_{o} sin θ / g)

       x = v₀² /g      2 cos θ sin θ

       x = v₀² sin 2θ / g

at the point where the receiver receives the ball is at the same height, so this coincides with the range of the projectile launch,

b) The acceleration to which the ball is subjected is equal in the rise and fall, therefore it takes the same time for both parties, let's find the rise time

at the highest point the vertical speed is zero

          v_{y} = v_{oy} - gt

          v_{y} = 0

           t = v_{oy} / g

           t = v₀ sin θ / g

as the time to get on and off is the same the total time or flight time is

           t_total = 2 t

           t_total = 2 v₀ sin θ / g

c) we calculate

          x = 13.5 2 sin (2 32) / 9.8

          x = 16.7 m

4 0
3 years ago
With regard to pneumatic mechanical devices which afford protection against the formation of ice, which of the following stateme
Andreyy89

Answer:

the answer is The pneumatic mechanical device can only be used as a de-icing device.

Explanation:

An ice protection system prevents the formation of ice, or enables the aircraft to shed the ice before it can grow to a dangerous thickness. Ice protection systems are designed to keep atmospheric ice from accumulating on aircraft surfaces such as wings, propellers and engine intakes.

The pneumatic mechanical device is the Pneumatic deicing boots which was invented by the Goodrich Corporation in 1923. The pneumatic boot is usually made of layers of rubber, with one or more air chambers between the layers.

Any design which utilizes either a mechanical means of breaking the bond of ice to the surface, or which operates on a periodic cycle, is necessarily a de-ice system.

4 0
4 years ago
A sound with an intensity greater than_____ dB can cause damage to human ears.
sergiy2304 [10]

85 decibels or higher can cause damage to the human ear. Decibels is the value of the measurement of sound. Hearing loss can be caused by noise coming from a loud sound. Noise induced hearing loss maybe permanent loss or temporary loss. Examples of activities that can give you a noise induced hearing loss is target shooting, listening to music in your earphones that have a high volume, and using lawnmowers. 

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4 years ago
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