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Sladkaya [172]
3 years ago
12

a bucket of water of mass 20kg is pulled at a constant velocity up to a platform 40 meters above the ground. this takes 10 minut

es , during which time 5kg of water drips out at a steady rate through a hole in the bottom . find the work required to raise the bucket to the platform.
Physics
1 answer:
erma4kov [3.2K]3 years ago
5 0
<span>Taking into account the information above, we know the average mass of the bucket of water may be m=20-5/2=17.5kg. As the bucket of water is pulled at a "constant velocity" the work required to raise the bucket to the platform transformed into the potential energy of the bucket of water. That is why it should be W=mgh=17.5*9.8*40=6860J</span>
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A ball is thrown straight up into the air and passes a window 3 seconds after being released. It passes the same window on its w
melomori [17]

The  initial velocity of the ball is 55.125 m/s.

<h3>Initial velocity of the ball</h3>

The initial velocity of the ball is calculated as follows;

During upward motion

h = vi - ¹/₂gt²

h = vi - 0.5(9.8)(3²)

h = vi - 44.1 ----------------- (1)

During downward motion

h = vi + ¹/₂gt²

h = 0 + 0.5(9.8)(1.5)²

h = 11.025 ----------- (2)

solve (1) and (2) together, to determine the initial velocity of the ball

11.025 = vi - 44.1

vi = 11.025 + 44.1

vi = 55.125 m/s

Thus, the  initial velocity of the ball is 55.125 m/s.

Learn more about initial velocity here: brainly.com/question/19365526

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8 0
1 year ago
There is a 50 g sample of Ra-229. It has a half-life of 4 minutes.
Sloan [31]

Via half-life equation we have:


A_{final}=A_{initial}(\frac{1}{2})^{\frac{t}{h} }


Where the initial amount is 50 grams, half-life is 4 minutes, and time elapsed is 12 minutes.  By plugging those values in we get:

A_{final}=50(\frac{1}{2})^\frac{12}{4}=50(\frac{1}{2})^{3}=50(\frac{1}{8})=6.25g


There is 6.25 grams left of Ra-229 after 12 minutes.

4 0
3 years ago
A 850-kg sports car accelerates from rest to 95 km/h in 6.8 s .
swat32

From the calculations, the power expended is 43650 W.

<h3>What is the power expended?</h3>

Now we can find the acceleration from;

v = u + at

u = 0 m/s

v =  95 km/h or 26.4 m/s

t =  6.8 s

a = ?

Now

v = at

a = v/t

a = 26.4 m/s/ 6.8 s

a = 3.88 m/s^2

Force = ma = 850-kg * 3.88 m/s^2 = 3298 N

The distance covered is obtained from;

v^2 = u^2 + 2as

v^2 = 2as

s = v^2/2a

s = (26.4)^2/2 * 3.88

s = 696.96/7.76

s = 90 m

Now;

Work = Fs

Work =  3298 N * 90 m = 296820 J

Power =  296820 J/ 6.8 s

= 43650 W

Learn more about power expended:brainly.com/question/11579192

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5 0
2 years ago
A fullback preparing to carry the football starts from rest and accelerates straight ahead. He is handed the ball just before he
RideAnS [48]

Answer:

x=4.06m

Explanation:

A body that moves with constant acceleration means that it moves in "a uniformly accelerated movement", which means that if the velocity is plotted with respect to time we will find a line and its slope will be the value of the acceleration, it determines how much it changes the speed with respect to time.

When performing a mathematical demonstration, it is found that the equations that define this movement are as follows.

Vf=Vo+a.t  (1)\\\\

{Vf^{2}-Vo^2}/{2.a} =X(2)\\\\

X=Xo+ VoT+0.5at^{2}    (3)\\

Where

Vf = final speed

Vo = Initial speed

T = time

A = acceleration

X = displacement

In conclusion to solve any problem related to a body that moves with constant acceleration we use the 3 above equations and use algebra to solve

for this problem

Vf=7.6m/s

t=1.07

Vo=0

we can use the ecuation number one to find the acceleration

a=(Vf-Vo)/t

a=(7.6-0)/1.07=7.1m/s^2

then we can use the ecuation number 2 to find the distance

{Vf^{2}-Vo^2}/{2.a} =X

(7.6^2-0^2)/(2x7.1)=4.06m

4 0
3 years ago
A 60-W light bulb radiates electromagnetic waves uniformly in all directions. At a distance of 1.0 mm from the bulb, the light i
slega [8]

Answer:

The appropriate solution is:

(a) \frac{1}{4}(I_o)

(b) \frac{1}{4} (u_o)

(c) \frac{1}{2}B_o

Explanation:

According to the question, the value is:

Power of bulb,

= 60 W

Distance,

= 1.0 mm

Now,

(a)

⇒  \frac{I}{I_o} =\frac{r_o_2}{r_2}

On applying cross-multiplication, we get

⇒  I=I_o\times \frac{1_2}{2^2}

⇒     =I_o\times \frac{1}{4}

⇒     =\frac{1}{4} (I_o)

(b)

As we know,

⇒ \frac{u}{u_o} =\frac{I}{I_o}

By putting the values, we get

⇒ u=\frac{1}{4}(u_o)

(c)

⇒ \frac{B^2}{B_o^2} =\frac{u}{u_o}

         =\frac{I}{I_o}

⇒ B=B_o\times \sqrt{\frac{1}{4} }

⇒     =\frac{1}{2}(B_o)

4 0
3 years ago
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