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4 years ago

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Before you conduct your experiment, you need to form a hypothesis. A hypothesis is a prediction of what you think will happen in

the experiment. The hypothesis is a statement that describes “if” a certain set of circumstances are present “then” there will be a specific result that will occur. Hint on how to write a hypothesis: If____________________then_______________.

1 answer:

Stolb23 [73]4 years ago

5 0

Example: A apple rotting.

If I put my apple in a fridge, then it would not rot as fast because it is in a cooled area. (example)

Hope it helps! Brainiest Answer would be amazing!

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Which of the following best describes the gas trapped in a sealed balloon?

aliina [53]

"C) The movement of the gas particles keeps the balloon inflated" best describes the gas trapped in a sealed balloon, although the movement varies with the heat of the gas.

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3 years ago

Are noble gases nonreactive elements?

sashaice [31]

Answer:

Noble gases are nonreactive elements.

Explanation:

We call Group 18 of the Periodic Table "Noble gases" because they are inert gases. They do not like to bond with other elements.

The reason why is because their outermost shell for electrons is full. These electrons, called valence electrons, are are completely maxed out and therefore makes the element stable. This in turn makes it so that it doesn't really bond with other elements.

4 0

3 years ago

Read 2 more answers

The stopping distance d of a car after the brakes are applied varies directly as the square of the speed r. If a car travelling

Crank

270/70^2 = x/80^2

Cross multiply

270 (6400) = 4900x

x = 270(6400)/4900

352 and 32/49 feet

Hope this helps

4 0

3 years ago

Effciency of a lever is never 100% or more. why?Give reason

Troyanec [42]

Answer:

Ideally, the work output of a lever should match the work input. However, because of resistance, the output power is nearly always be less than the input power. As a result, the efficiency would go below $100\%$ .

Explanation:

In an ideal lever, the size of the input and output are inversely proportional to the distances between these two forces and the fulcrum. Let $D_\text{in}$ and $D_\text{out}$ denote these two distances, and let $F_\text{in}$ and $F_\text{out}$ denote the input and the output forces. If the lever is indeed idea, then:

$F_\text{in} \cdot D_\text{in} = F_\text{out} \cdot D_\text{out}$ .

Rearrange to obtain:

$\displaystyle F_\text{in} = F_\text{out} \cdot \frac{D_\text{out}}{D_\text{in}}$

Class two levers are levers where the perpendicular distance between the fulcrum and the input is greater than that between the fulcrum and the output. For this ideal lever, that means $D_\text{in} > D_\text{out}$ , such that $F_\text{in} < F_\text{out}$ .

Despite $F_\text{in} < F_\text{out}$ , the amount of work required will stay the same. Let $s_\text{out}$ denote the required linear displacement for the output force. At a distance of $D_\text{out}$ from the fulcrum, the angular displacement of the output force would be $\displaystyle \frac{s_\text{out}}{D_\text{out}}$ . Let $s_\text{in}$ denote the corresponding linear displacement required for the input force. Similarly, the angular displacement of the input force would be $\displaystyle \frac{s_\text{in}}{D_\text{in}}$ . Because both the input and the output are on the same lever, their angular displacement should be the same:

$\displaystyle \frac{s_\text{in}}{D_\text{in}} =\frac{s_\text{out}}{D_\text{out}}$ .

Rearrange to obtain:

$\displaystyle s_\text{in}=s_\text{out} \cdot \frac{D_\text{in}}{D_\text{out}}$ .

While increasing $D_\text{in}$ reduce the size of the input force $F_\text{in}$ , doing so would also increase the linear distance of the input force $s_\text{in}$ . In other words, $F_\text{in}$ will have to move across a longer linear distance in order to move $F_\text{out}$ by the same $s_\text{out}$ .

The amount of work required depends on both the size of the force and the distance traveled. Let $W_\text{in}$ and $W_\text{out}$ denote the input and output work. For this ideal lever:

$\begin{aligned}W_\text{in} &= F_\text{in} \cdot s_\text{in} \\ &= \left(F_\text{out} \cdot \frac{D_\text{out}}{D_\text{in}}\right) \cdot \left(s_\text{out} \cdot \frac{D_\text{in}}{D_\text{out}}\right) \\ &= F_\text{out} \cdot s_\text{out} = W_\text{out}\end{aligned}$ .

In other words, the work input of the ideal lever is equal to the work output.

The efficiency of a machine can be measured as the percentage of work input that is converted to useful output. For this ideal lever, that ratio would be $100\%$ - not anything higher than that.

On the other hand, non-ideal levers take in more work than they give out. The reason is that because of resistance, $F_\text{in}$ would be larger than ideal:

$\displaystyle F_\text{in} = F_\text{out} \cdot \frac{D_\text{out}}{D_\text{in}} + F(\text{resistance})$ .

As a result, in real (i.e., non-ideal) levers, the work input will exceed the useful work output. The efficiency will go below $100\%$ ,

4 0

3 years ago

A block (mass m1) lying on a frictionless inclined plane is connected to a mass (mass m2) by a massless cord passing over a pull

azamat

Answer:

a) System aceleration:

$a=\frac{g(m_2-m_1sin(\theta))}{m_1+m_2}$

b) Direction of movement:

The block $m_1$ down the plane when the acceleration is negative. This occur when:

$m_2-m_1sin(\theta)$

The block $m_2$ up the plane when the acceleration is positive. This occur when:

$m_2-m_1sin(\theta)>0$

Explanation:

For the block $m_1$ the move direction is parallel (||) to the plane

$\sum F_{||}=m_1a=T-sin(\theta)mg$ (1)

For the block $m_2$ the move direction is vertical (y)

$\sum F_y=m_2a=m_2g-T$ (2)

Both blocks are connected with the same cable, therefore, the tension on the cable and the acceleration is the same for both.

Solving the equation 2 for T:

$T=m_2g-m_2a$ (3)

replacing (3) in the equation (1)

$m_2g-m_2a- m_1gsin(\theta)=m_1a$ (4)

solving (4) for a:

$a=\frac{g(m_2-m_1sin(\theta))}{m_1+m_2}$

8 0

3 years ago