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2 years ago

Its a motion phisic question but im a little confused. Help me fast please.

Physics

1 answer:

Alenkinab [10]2 years ago

3 0

6: Short way: it cannot be 2.5, 3, or 5 because up to 5 seconds it only has positive velocity so it must be moving forwards.

Long Way: Velocity is in m / s, multiply that by time (s) to get m or displacement. From 0->5 you have a triangle under the curve, (1/2)(5)(20) = 50 meters displaced positive, you need to then look when velocity is under the curve and use a similar equation to solve for the area but make the answer negative. Find the point where it equals -50 and that is where it will have returned.

Answer to 6: B

7. I cannot see the problem enough to answer this. Just know if the line is above 0 velocity is positive so it is moving the direction it started, when it goes below 0 velocity is negative so it is moving opposite direction it started.

8. Accelration is change in velocity. Whatever the slope of the velocity graph is acceleration. At t=8 the slope is 0 because it is not going up or down.

Answer to 8: A

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A rotating water pump works by taking water in at one side of a rotating wheel, and expelling it from the other side. If a pump

Xelga [282]

Answer:

Explanation:

initial angular velocity, ωo = 0 rad/s

angular acceleration, α = 30.5 rad/s²

time, t = 9 s

radius, r = 0.120 m

let the velocity is v after time 9 s.

Use first equation of motion for rotational motion

ω = ωo + αt

ω = 0 + 30.5 x 9

ω = 274.5 rad/s

v = rω

v = 0.120 x 274.5

v = 32.94 m/s

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2 years ago

How much charge can be placed on a capacitor with air between the plates before it breaks down if the area of each plate is 4.00

klio [65]

Explanation:

Let us assume that the separation of plate be equal to d and the area of plates is $9 \times 10^{-4} m^{2}$ . As the capacitance of capacitor is given as follows.

C = $\frac{\epsilon_{o}A}{d}$

It is known that the dielectric strength of air is as follows.

E = $3 \times 10^{6} V/m$

Expression for maximum potential difference is that the capacitor can with stand is as follows.

dV = E × d

And, maximum charge that can be placed on the capacitor is as follows.

Q = CV

= $\frac{\epsilon_{o} A}{d} \times E \times d$

= $\epsilon_{o}AE$

= $8.85 \times 10^{-12} \times 3 \times 10^{6} \times 4 \times 10^{-4}$

= $1.062 \times 10^{-8} C$

or, = 10.62 nC

Thus, we can conclude that charge on capacitor is 10.62 nC.

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2 years ago

Water is leaking out of an inverted conical tank at a rate of 10,500 cm3/min at the same time that water is being pumped into th

satela [25.4K]

The tank has a volume of $\dfrac\pi3R^2H$ , where $H=6\,\rm m$ is its height and $R=\dfrac d2=2\,\rm m$ is its radius.

At any point, the water filling the tank and the tank itself form a pair of similar triangles (see the attached picture) from which we obtain the following relationship:

$\dfrac26=\dfrac rh\implies r=\dfrac h3$

The volume of water in the tank at any given time is

$V=\dfrac\pi3r^2h$

and can be expressed as a function of the water level alone:

$V=\dfrac\pi3\left(\frac h3\right)^2h=\dfrac\pi{27}h^3$

Implicity differentiating both sides with respect to time $t$ gives

$\dfrac{\mathrm dV}{\mathrm dt}=\dfrac\pi9h^2\,\dfrac{\mathrm dh}{\mathrm dt}$

We're told the water level rises at a rate of $\dfrac{\mathrm dh}{\mathrm dt}=20\,\frac{\rm cm}{\rm min}$ at the time when the water level is $h=2\,\mathrm m=200\,\mathrm{cm}$ , so the net change in the volume of water $\dfrac{\mathrm dV}{\mathrm dt}$ can be computed:

$\dfrac{\mathrm dV}{\mathrm dt}=\dfrac\pi9(200\,\mathrm{cm})^2\left(20\,\dfrac{\rm cm}{\rm min}\right)=\dfrac{800,000\pi}9\,\dfrac{\mathrm{cm}^3}{\rm min}$

The net rate of change in volume is the difference between the rate at which water is pumped into the tank and the rate at which it is leaking out:

$\dfrac{\mathrm dV}{\mathrm dt}=(\text{rate in})-(\text{rate out})$

We're told the water is leaking out at a rate of $10,500\,\frac{\mathrm{cm}^3}{\rm min}$ , so we find the rate at which it's being pumped in to be

$\dfrac{800,000\pi}9\,\dfrac{\mathrm{cm}^3}{\rm min}=(\text{rate in})-10,500\,\dfrac{\mathrm{cm}^3}{\rm min}$

$\implies\text{rate in}\approx289,753\,\dfrac{\mathrm{cm}^3}{\rm min}$

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2 years ago

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Leto [7]

Explanation:

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