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svet-max [94.6K]

4 years ago

13

A woman stands on a bathroom scale in a motionless elevator. When the elevator begins to move, the scale briefly reads only 0.64

of her regular weight. Calculate the magnitude of the acceleration of the elevator.

1 answer:

Galina-37 [17]4 years ago

6 0

Answer:

The downwards acceleration is 3.53 m/s2.

Explanation:

Let the true weight is m g.

The reading of the balance, R = 0.64 mg

Let the acceleration is a.

As the apparent weight is less than the true weight so the elevator goes down wards with some acceleration.

Use Newton's second law

m g - R = m a

m g - 0.64 m g = m a

0.36 g = a

a = 3.53 m/s2

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A uniform solid disk and a uniform ring are place side by side at the top of a rough incline of height h.

nadezda [96]

Explanation:

velocity of disc $=\sqrt((gh)/0.75)$

lets call (h) 1 m to make it simple.

= 3.614 m/s

$\sqrt((4/3) x 1 x 9.8) = 3.614$ m/s pointing towards this:

$4×V_d=\sqrt(4/3hg)$

$V_h=\sqrt(hg)$

velocity of hoop= $\sqrt(gh)$

lets call (h) 1m to make it simple again.

$\sqrt(9.8 x 1) = 3.13$ m/s

$\sqrt(gh) = sqrt(hg)so [tex]4×V_d= \sqrt(4/3hg)V_h=\sqrt(hg)$

The disc is the fastest.

While i'm on this subject i'll show you this:

Solid ball $=0.7v^2= gh$

solid disc $= 0.75v^2 = gh$

hoop $=v^2=gh$

The above is simplified from linear KE + rotational KE, the radius or mass makes no difference to the above formula.

The solid ball will be the faster of the 3, like above i'll show you.

solid ball: velocity $=\sqrt((gh)/0.7)$

let (h) be 1m again to compare.

$\sqrt((9.8 x 1)/0.7) = 3.741$ m/s

solid disk speed $=\sqrt((gh)/0.75)$

uniform hoop speed $=\sqrt(gh)$

solid sphere speed $=\sqrt((gh)/0.7)$

8 0

3 years ago

A conducting coil of 1470 turns is connected to a galvanometer, and the total resistance of the circuit is 56.0 . The area of ea

Damm [24]

Answer:

B = - 1.51 10⁻⁷ T

Explanation:

For this exercise we can use Faraday's law of induction

E = - $- \frac{d \phi _B}{dt} = - \frac{d (B A cos \theta )}{dt}$

In this case, they indicate that the normal and the magnetite field are in the same direction, so the angle is zero (cos 0 = 1), they give the area of the loop A = 4.32 10⁻⁴ m² and since we have N = 1470 turns in each one a voltage is induced

E = - N B A

B = -E A / N (1)

we find the induced voltage with ohm's law

V = i R

where the current is defined by

i = Q / t

we substitute

V = Q R / t

let's calculate

V = 9.18 10-3 56.0 / t

We must assume a time normally is t = 1 s

V = 0.514 V

this is the voltage in the circuit which must be the induced voltage V = E

we substitute in 1

B = - 0.514 4.32 10⁻⁴ / 1470

B = - 1.51 10⁻⁷ T

3 0

3 years ago

Which cannot be separated into simpler substances?

marin [14]

Answer:

An element is a pure substance that cannot be separated into simpler substances by chemical or physical means. There are about 117 elements.

Explanation:

6 0

3 years ago

Read 2 more answers

1. A SUV along with 5 passengers has a mass of 3500 kg. It has a driving force of 2500 N directed along west on a perfectly hori

Dovator [93]

Answer:

The net acceleration of the SUV is 0.429 meters per square second due west.

Explanation:

Statement is incomplete. Description is presented below:

<em>A SUV along with 5 passengers has a mass of 3500 kg. It has a driving force of 2500 N directed along west on a perfectly horizontal road. The surface of the road exerts a resistance force of 500 N due east. At the same time a high wind is blowing a force of 500 N due east in the opposite direction of the car's drive force. Does the car has any acceleration? If yes, then what are the magnitude and direction of the car's acceleration?</em>

According to Newton's Laws of Motion, the SUV will accelerate if and only if net acceleration is different of zero. Let suppose as positive the direction of driving force ( $F$ ), measured in newtons:

$\Sigma F = F - R -f = F_{net}$ (1)

Where:

$R$ - Resistance force, measured in newtons.

$f$ - Wind force, measured in newtons.

$F_{net}$ - SUV net force, measured in newtons.

If we know that $F = 2500\,N$ , $R = 500\,N$ and $f = 500\,N$ , then net force experimented by the SUV is:

$F_{net} = 2500\,N-500\,N-500\,N$

$F_{net} = 1500\,N$

The car has acceleration.

By definition of force for systems with constant mass, we calculate the acceleration of the vehicle below:

$a_{net} = \frac{F_{net}}{m}$ (2)

Where $m$ is the mass of the SUV, measured in kilograms.

If we know that $F_{net} = 1500\,N$ and $m = 3500\,kg$ , then the net acceleration of the car is:

$a_{net} = \frac{1500\,N}{3500\,kg}$

$a_{net} = 0.429\,\frac{m}{s^{2}}$

The net acceleration of the SUV is 0.429 meters per square second due west.

8 0

3 years ago

A truck moves 60 km West, and then 80 km North, and then

stira [4]

$▪▪▪▪▪▪▪▪▪▪▪▪▪ {\huge\mathfrak{Answer}}▪▪▪▪▪▪▪▪▪▪▪▪▪▪$

Distance travelled by the truck is ~

$\boxed{240 \: \: km}$

And it's displacement is ~

$\boxed{0 \: \: km}$

$\large \boxed{ \mathfrak{Step\:\: By\:\:Step\:\:Explanation}}$

See the diagram in attachment for reference ~

Let O be the initial point, It travels 60 km towards west till point B and then 80 km towards north till point P and returns to initial point O in a straight line, now as we can observe here, it forms a right angled Triangle.

The measure of two legs is 60 km and 80 km, let's find the hypotenuse ~

According to Pythagoras theorem ~

hypotenuse² = sum of squares of other two legs

that is ~

$h {}^{2} = 60 {}^{2} + 80 {}^{2}$

${h}^{2} = 3600 + 640 0$

$h {}^{2} = 10000$

$h = \sqrt{10000}$

$h = \sqrt{100 \times 100}{}$

$h = 100 \: \: km$

So, the distance between the point A and O is 100 km

Now, The total distance is equal to the distance covered through actual path that is ~

60 km + 80 km + 100 km

240 km

And displacement is the distance between the final point and initial point, but since the truck returns to the point from where it started the journey, so the final and initial point is same therefore displacement is equal to 0.

4 0

3 years ago