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3 years ago

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A lever is being used to move a heavy stone from a garden. The stone weighs 250 newtons. The board used as a lever is 6 meters l

ong. If two of the board's meters will be used as he resistance arm how much force will be needed to move the rock?

1 answer:

DerKrebs [107]3 years ago

7 0

Answer:

Force = 125 [N]

Explanation:

In the attached image we can see a sketch of the lever system.

And if we make a sum of moments at the point O equal to zero (0).

In the equation showed in the image, we can determinate the force that we need

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A runner is jogging in a straight line at a

Fiesta28 [93]

Answer:

Total distance traveled by bird is 10.5 km.

Explanation:

Given that,

Velocity of runner= 8.4 km/hr

Distance = 6.3 km

Velocity of bird = 42 km/hr

Suppose, How far does the bird travel?

We need to calculate the time of bird

Using formula of time

$t=\dfrac{d}{v_{b}}$

Put the value into the formula

$t=\dfrac{6.3}{42}$

$t=0.15\ hr$

We need to calculate the distance runner travels during time period

Using formula of distance

$d=v_{r}\times t$

$d=8.4\times0.15$

$d=1.26\ km$

We need to calculate the distance of runner to FL

Using distance

$d'=6.3-1.26$

$d'=5.04\ km$

We need to calculate the net closing speed between runner and bird

Using speed

$v'=v_{r}+v_{b}$

$v'=8.4+42$

$v'=50.4\ km/hr$

We need to calculate the time for runner and bird to meet

Using formula of time

$t=\dfrac{d}{v'}$

Put the value into the formula

$t=\dfrac{5.04}{50.4}$

$t=0.1\ hr$

We need to calculate the distance covered by runner

Using formula of distance

$d=vt$

Put the value into the formula

$d=8.4\times0.1$

$d=0.84\ km$

We need to calculate the distance covered by bird to runner

Using formula of distance

$d=vt$

Put the value into the formula

$d=42\times0.1$

$d=4.2\ km$

We need to calculate the total distance

Using distance

$D=6.3+4.2$

$D=10.5\ km$

Hence, Total distance traveled by bird is 10.5 km.

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3 years ago

Emily’s vacuum cleaner has a power rating of 200 watts. If the vacuum cleaner does 360,000 joules of work,

gtnhenbr [62]

Divide 360000 by 200 to get 1800 seconds, or half of hour.

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4 years ago

Photons of what minimum frequency are required to remove electrons from gold? note: the work function for gold is 4.8 ev.

kolbaska11 [484]

In the photoelectric effect, the energy given by the incoming photon is used partially to extract the electron from the metal (work function) and the rest is converted into kinetic energy of the electron:
$hf= \phi + K$
where
hf is the energy of the photon, with h being the Planck constant and f the frequency of the photon
$\phi$ is the work function
K is the kinetic energy of the electron

When K=0, we have the minimum energy required to extract the electron from the metal, so the equation becomes
$hf= \phi$ (1)

If we convert the work function of gold into Joules:
$\phi=4.8 eV = 7.69 \cdot 10^{-19}J$
We can re-arrange eq.(1) to find the minimum energy of the photon:
$f= \frac{\phi}{h}= \frac{7.69 \cdot 10^{-19}J}{6.6 \cdot 10^{-34} Js} =1.17 \cdot 10^{15} Hz$

5 0

4 years ago

A go-kart accelerates at a rate

stira [4]

Answer:

if it is at a speed of 12.5 m / s it would take 2 minutes

Explanation:

4 0

4 years ago

: Two containers have a substantial amount of the air evacuated out of them so that the pressure inside is half the pressure at

ser-zykov [4K]

Complete Question

Two containers have a substantial amount of the air evacuated out of them so that the pressure inside is half the pressure at sea level. One container is in Denver at an altitude of about 6,000 ft and the other is in New Orleans (at sea level). The surface area of the container lid is A=0.0155 m. The air pressure in Denver is PD = 79000 Pa. and in New Orleans is PNo = 100250 Pa. Assume the lid is weightless.

Part (a) Write an expression for the force FNo required to remove the container lid in New Orleans.

Part (b) Calculate the force FNo required to lift off the container lid in New Orleans, in newtons.

Part (c) Calculate the force Fp required to lift off the container lid in Denver, in newtons.

Part (d) is more force required to lift the lid in Denver (higher altitude, lower pressure) or New Orleans (lower altitude, higher pressure)?

Answer:

a

The expression is $F_{No} = A [P_{No} - \frac{P_{sea}}{2}]$

b

$F_{No}= 7771.125 \ N$

c

$F_p = 2.2*10^{6} N$

d

From the value obtained we can say the that the force required to open the lid is higher at Denver

Explanation:

The altitude of container in Denver is $d_D = 6000 \ ft = 6000 * 0.3048 = 1828.8m$

The surface area of the container lid is $A = 0.0155m^2$

The altitude of container in New Orleans is sea-level

The air pressure in Denver is $P_D = 79000 \ Pa$

The air pressure in new Orleans is $P_{ro} = 100250 \ Pa$

Generally force is mathematically represented as

$F_{No} = \Delta P A$

So we are told the pressure inside is is half the pressure the at sea level so the the pressure acting on the container would

The pressure at sea level is a constant with a value of

$P_{sea} = 101000 Pa$

So the $\Delta P$ which is the difference in pressure within and outside the container is

$\Delta P = P_{No} - \frac{P_{sea}}{2}$

Therefore

$F_{No} = A [P_{No} - \frac{P_{sea}}{2}]$

Now substituting values

$F_{No} = 0.0155 [100250 - \frac{101000}{2}]$

$F_{No}= 7771.125 \ N$

The force to remove the lid in Denver is

$F_p = \Delta P_d A$

So we are told the pressure inside is is half the pressure the at sea level so the the pressure acting on the container would

The pressure at sea level is a constant with a value of

$P_{sea} = 101000 Pa$

At sea level the air pressure in Denver is mathematically represented as

$P_D = \rho g h$

=> $g = \frac{P_D}{\rho h}$

Let height at sea level is h = 1

The air pressure at height $d_D$

$P_d__{D}} = \rho gd_D$

=> $g = \frac{P_d_D}{\rho d_D}$

Equating the both

$\frac{P_D}{\rho h} = \frac{P_d_D}{\rho d_D}$

$P_d_D = P_D * d_D$

Substituting value

$P_d__{D}} = 1828.2 * 79000$

$P_d__{D}} = 1.445*10^{8} Pa$

So

$\Delta P_d = P_{d} _D - \frac{P_{sea}}{2}$

=> $\Delta P_d = 1.445 *10^{8} - \frac{101000}{2}$

$\Delta P_d = 1.44*10^{8}Pa$

So

$F_p = \Delta P_d A$

$= 1.44*10^8 * 0.0155$

$F_p = 2.2*10^{6} N$

6 0

4 years ago