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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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A person is riding a bicycle, and its wheels have an angular velocity of 10.7 rad/s. Then, the brakes are applied and the bike i
Scilla [17]

Answer:

(a) t = 22.9 s

(b) α= - 0.467 rad/s²

Explanation:

The uniformly accelerated circular movement, is a circular path movement in which the angular acceleration is constant.

We apply the equations of circular motion uniformly accelerated :

ωf ²=  ω₀² + 2*α*θ  Formula (1)

ωf= ω₀ + α*t Formula (2)

Where:

θ : angle that the body has rotated in a given time interval (rad)

α : angular acceleration (rad/s²)

t : time interval (s)

ω₀ : initial angular speed ( rad/s)

ωf : final angular speed ( rad/s)

Data

θ =  19.5 revolutions  : angular displacement of each wheel or angle that the  wheel has rotated in a given time interval

ω₀= 10.7 rad/s :  initial angular speed of the Wheel ( rad/s)

ωf = 0 : final angular speed  of the Whee( rad/s)

Calculating of the angular acceleration (α )

We replace data in the fómula (1),considering that 1 revolution is equal to 2π radians :

ωf ²=  ω₀² + 2*α*θ

(0 )²=  (10.7)² + 2*α*(19.5*2*π )

0= 114.49 + (245.04)*α

-114.49 =  (245.04)*α

α= (-114.49) /(245.04)

α= -114.49 /(245.04)

α= -0.467 rad/s²

Time does it take for the bike to come to rest

We replace data in the formula (2)

ωf = ω₀ + α*t

0 =  10.7 + -0.467*t

-10.7  = - 0.467*t    we multiply by (-1) both sides of the equation :

10.7  = 0.467*t  

t = 10.7 / 0.467

t = 22.9 s

3 0
3 years ago
a block measuring 20cm by 10cm by 5cm rests on a flat surface. The block has a weight of 3N. Determine the maximum pressure it e
Lady_Fox [76]
Max preassure = force / min area
= 3N / 0.1 x 0.05
= 600N/m(squared)
Copy off of the picture below itll help better, its what someone sent me when i asked this question

4 0
4 years ago
A 16.0kg canoe moving to the left at 12.5m/s makes an elastic head-on collision with a 14.0kg raft moving to the right at 16.0m/
kherson [118]

The canoe is moving at 14.1 m/s to the right after the collision.

Explanation:

According to the law of conservation of momentum, in absence of external forces the total momentum of the system must be conserved before and after the collision. So we can write:

p_i = p_f\\m_1 u_1 + m_2 u_2 = m_1 v_1 + m_2 v_2

where:

m_1 = 16.0 kg is the mass of the canoe

u_1 = -12.5 m/s is the initial velocity of canoe (we take right as positive direction, and since the canoe is moving to the left, its velocity is negative)

v_1 is the final velocity of the canoe

m_2 = 14.0 kg is the mass of the raft

u_2 = +16.0 m/s is the initial velocity of the raft

v_2 = -14.4 m/s is the final velocity of the raft

Re-arranging the equation and substituting the values, we find: the final velocity of the canoe:

v_1 = \frac{m_1 u_1 + m_2 u_2-m_2 v_2}{m_1}=\frac{(16.0)(-12.5)+(14.0)(16.0)-(14.0)(-14.4)}{16.0}=+14.1 m/s

So, the canoe is moving at 14.1 m/s to the right after the collision.

Learn more about momentum:

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5 0
3 years ago
Part 1 :
tatuchka [14]

1) 9.57 N

We have two forces applied on the apple:

- The force of gravity, in the downward direction:

W = 9.42 N

- The force exerted by the wind, in the horizontal direction (to the right):

Fw = 1.68 N

The two forces are perpendicular to each other, so we can find the magnitude of the net force by using Pythagorean's theorem.

Therefore, we have:

F=\sqrt{W^2+F_w^2}=\sqrt{(9.42)^2+(1.68)^2}=9.57 N

2) 10^{\circ}

The direction of the net external force, measured from the downward vertical, can be measured using the following formula:

\theta = tan^{-1}(\frac{F_x}{F_y})

where

F_x is the force in the horizontal direction

F_y is the force in the vertical direction

In this problem,

F_x = F_w = 1.68 N

F_y = W = 9.42 N

and so we find:

\theta = tan^{-1}(\frac{1.68}{9.42})=10^{\circ}

4 0
3 years ago
Ice core samples are used to measure…
blsea [12.9K]

Answer:

the correct answer is A

6 0
3 years ago
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