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3 years ago

I NEED HELP PLEASE, THANKS!

Physics

1 answer:

Travka [436]3 years ago

6 0

Explanation:

When a person is standing still, the forces acting on them (weight force pulling down and normal force pushing up) are equal and opposite, so the net force is balanced. So the person will continue to be at rest, unless the net force becomes unbalanced.

When a person falls with a parachute, the forces acting on them (weight force pulling down and air resistance pushing up) are equal and opposite, so the net force is balanced. So the person will continue to fall at the same speed until the net force becomes unbalanced.

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Vertical Motion

harina [27]

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3 0

2 years ago

Salmon often jump waterfalls to reach their breeding grounds. Starting downstream, 3.18 m away from a waterfall 0.294 m in heigh

Karolina [17]

Answer:

v = 7.65 m/s

t = 0.5882 s

Explanation:

We are told that the salmon started downstream, 3.18 m away from a waterfall.

Thus, range = 3.18 m

Since the horizontal velocity component is constant, then;

Range = vcosθ × t

Thus,

vcosθ × t = 3.18 - - - (eq 1)

We are told the salmon reached a height of 0.294 m

Thus, using distance equation;

s = v_y•t + ½gt²

g will be negative since motion is against gravity.

s = v_y•t - ½gt²

Thus;

0.294 = v_y•t - ½gt²

v_y = vsinθ

Thus;

0.294 = vtsinθ - ½gt² - - - (eq 2)

From eq(1), making v the subject, we have;

v = 3.18/tcosθ

Plugging into eq 2,we have;

0.294 = (3.18/tcosθ)tsinθ - ½gt²

0.295 = 3.18tanθ - ½gt²

We are given g = 9.81 m/s² and θ = 45°

0.295 = (3.18 × tan 45) - ½(9.81) × t²

0.295 = 3.18 - 4.905t²

3.18 - 0.295 = 4.905t²

4.905t² = 2.885

t = √2.885/4.905

t = 0.5882 s

Thus;

v = 3.18/(0.5882 × cos45)

v = 7.65 m/s

8 0

2 years ago

If the humidity in a room of volume 410 m3 at 25 ∘C is 70%, what mass of water can still evaporate from an open pan? Express you

Keith_Richards [23]

Answer:

$m=1864.68\ g$

Explanation:

Given:

volume of air in the room, $V=410\ m^3$

temperature of the room, $T=25+273=298\ K$

Saturation water vapor pressure at any temperature T K is given as:

$p_{sw}=\frac{e^{(77.3450 + 0.0057\times T - \frac{ 7235}{T} )}}{T^{8.2}}$

putting T=298 K we have

$p_{sw}=3130\ Pa$

The no. of moles of water molecules that this volume of air can hold is:

Using Ideal gas law,

$P.V=n.R.T$

$n=\frac{P_{sw}.V}{R.T}$

$n=\frac{3130\times 410}{8.314\times 298}$

$n=518\ moles$ is the maximum capacity of the given volume of air to hold the moisture.

Currently we have 80% of n, so the mass of 20% of n:

$m=(20\%\ of\ n)\times M}$

where;

M= molecular mass of water

$m=0.2\times 518\times 18$

$m=1864.68\ g$ is the mass of water that can vaporize further.

3 0

2 years ago

Three resistors connected in series have potential differences across them labeled /\V1 , /\V2 , and /\V3. What expresses the po

Brrunno [24]

Answer:

$\Delta V=\Delta V_1+\Delta V_2+\Delta V_3$

Explanation:

We are given that three resistors R1, R2 and R3 are connected in series.

Let

Potential difference across $R_1=\Delta V_1$

Potential difference across $R_2=\Delta V_2$

Potential difference across $R_3=\Delta V_3$

We know that in series combination

Potential difference , $V=V_1+V_2+V_3$

Using the formula

$\Delta V=\Delta V_1+\Delta V_2+\Delta V_3$

Hence, this is required expression for potential difference.

3 0

3 years ago

Diya visited a tailor shop and bought home three cuttings of fabric A,B and C to study their properties. Diya tried burning the

andreev551 [17]

Answer:

Rayon

Wool

Silk Yarn

Explanation:

Rayon

This is Fabric A. Rayon basically burns very quickly even quicker than fabrics like cotton and linen. Its ash is gray in color. The rayon fabric smells of burning paper when it is burnt.

Wool:

This is Fabric B. Wool is basically hard to ignite. It burns slowly. Its ash is dark in color. The wool fabric smells of burning hair when it is burnt.

Silk Yarn:

This is Fabric C. The silk yarn shrinks from the flame when it is burned. It has a grayish black ash. The silk yarn fabric smells burnt meat of when it is burnt.

3 0

2 years ago