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3 years ago

5

Give an example of a system whose mass is not constant.

1 answer:

Sloan [31]3 years ago

8 0

A spinning top is the answer

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Need help solving this question.

MatroZZZ [7]

Answer:

See the answers below.

Explanation:

to solve this problem we must make a free body diagram, with the forces acting on the metal rod.

i)

The center of gravity of the rod is concentrated in half the distance, that is, from the end of the bar to the center there is 40 [cm]. This can be seen in the attached free body diagram.

We have only two equilibrium equations, a summation of forces on the Y-axis equal to zero, and a summation of moments on any point equal to zero.

For the summation of forces we will take the forces upwards as positive and the negative forces downwards.

ΣF = 0

$-15+T-W=0\\T-W=15$

Now we perform a sum of moments equal to zero around the point of attachment of the string with the metal bar. Let's take as a positive the moment of the force that rotates the metal bar counterclockwise.

ii) In the free body diagram we can see that the force acts at 18 [cm] of the string.

ΣM = 0

$(15*9) - (18*W) = 0\\135 = 18*W\\W = 7.5 [N]$

7 0

3 years ago

A bicyclist in the Tour de France crests a mountain pass as he moves at 18 km/h. At the bottom, 4.0 km farther, his speed is at

Allisa [31]

We are given:

v0 = initial velocity = 18 km/h

d = distance = 4 km

v = final velocity = 75 km/h

a =?

<span>
We can solve this problem by using the formula:</span>

v^2 = v0^2 + 2 a d

75^2 = 18^2 + 2 (a) * 4

5625 = 324 + 8a

<span>a = 662.625 km/h^2</span>

6 0

3 years ago

Two pianos each sound the same note simultaneously, but they are both out of tune. On a day when the speed of sound is 349 m/s,

SSSSS [86.1K]

Answer:

Time period between the successive beats will be 0.1703 sec

Explanation:

We have given speed of the sound v = 349 m/sec

Wavelength of piano $A\lambda _A=0.766m$

Wavelength of piano $B\lambda _B=0.776m$

So frequency of piano A $f_1=\frac{v}{\lambda _1}=\frac{349}{0.766}=455.61Hz$

Frequency of piano B $f_2=\frac{v}{\lambda _1}=\frac{349}{0.776}=449.74Hz$

So beat frequency f = 455.61 - 449.74 = 5.87 Hz

So time period $T=\frac{1}{f}=\frac{1}{5.87}=0.1703sec$

So time period between the successive beats will be 0.1703 sec

4 0

3 years ago

Which of the following is an example of distance equaling displacement?

AleksandrR [38]

Answer:

D

Explanation:

The student had displaced their in the class when she left. The phone is what's displaced and student leaving equals distance.

3 0

3 years ago

The voltage ???? in a simple electrical circuit is slowly decreasing as the battery wears out. The resistance ???? is slowly inc

zimovet [89]

Answer:

The change in current at $R =456 \Omega$ is $\frac{dI}{dt} = 7.032 * 10^{-5} A/s$

Explanation:

From the question we are told that

The resistance is $R = 465 \Omega$

The current is $I = 0.09A$

The change in voltage with respect to time is $\frac{dV}{dt} = - 0.03 V/s$

The change in resistance with time is $\frac{dR}{dt} = 0.03 \Omega /s$

According to ohm's law

$V = IR$

differentiating with respect to time using chain rule

$\frac{dV}{dt} = I \frac{dR}{dt} + R * \frac{dI}{dt}$

substituting value at R = 456

$-0.0327 = 0.09 * 0.03 + 456* \frac{dI}{dt}$

$\frac{dI}{dt} = 7.032 * 10^{-5} A/s$

6 0

3 years ago