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Nezavi [6.7K]
3 years ago
10

A ball is thrown vertically downwards with a speed 7.3 m/s from the top of a 51 m tall building. With what speed will it hit the

ground, in units of m/s? Assume that air resistance is negligible. Give the answer as a positive number.
Physics
2 answers:
ddd [48]3 years ago
8 0

Answer:

32.46m/s

Explanation:

Hello,

To solve this exercise we must be clear that the ball moves with constant acceleration with the value of gravity = 9.81m / S ^ 2

A body that moves with constant acceleration means that it moves in "a uniformly accelerated motion", 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 the follow

\frac {Vf^{2}-Vo^2}{2.a} =X

Where

Vf = final speed

Vo = Initial speed =7.3m/S

A = g=acceleration =9.81m/s^2

X = displacement =51m}

solving for Vf

Vf=\sqrt{Vo^2+2gX}\\Vf=\sqrt{7.3^2+2(9.81)(51)}=32.46m/s

the speed with the ball hits the ground is 32.46m/s

statuscvo [17]3 years ago
3 0

Answer:

The speed will be 33 m/s.

Explanation:

The equations for height and velocity of the ball are as follows:

y = y0 + v0 · t + 1/2 · g · t²

v = v0 + g · t

Where:

y = height at time "t".

y0 = initial height.

v0 = initial velocity.

t = time.

g = acceleration due to gravity (-9.8 m/s² considering the upward direction as positive)

v = velocity at time "t".

Let´s place the origin of the frame of reference on the ground and consider the upward direction as positive.

First, let´s find the time it takes the ball to reach the ground:

y = y0 + v0 · t + 1/2 · g · t²

When the ball hits the ground, y = 0. Then:

0 = 51 m - 7.3 m/s · t - 1/2 · 9.8 m/s² + t²

Solving the quadratic equation:

t = 2.6 s

Now, with this time, we can calculate the velocity at the moment when the ball hits the ground:

v = v0 + g · t

v = -7.3 m/s - 9.8 m/s² · 2.6 s

v = -33 m/s

The speed will be 33 m/s.

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Explanation:

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for P=4 and N=3600, f comes out to be 120 Hz.

So frequency of voltage produced is 120 Hz. But this is not practical. Generally 4-Pole generator has N=1500rpm(for 50 Hz) or 1800rpm for 60 Hz. Two pole generator can have N=3600rpm(f=60Hz).

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Hope It will be helpful!!!

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2 years ago
Four point charges of magnitudes +3q, -q, +2q, and -4q are arranged in the corners of a square of side length L. The charge -q c
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Answer:

d) 0 V

Explanation:

It can be showed that the potential due to a point charge q, to a distance d from the charge, can be expressed as follows:

V = \frac{k*q}{r}

where k = \frac{1}{4*\pi*\epsilon0} = 9e9 N*m2/C2

As the potential is an scalar, and is linear with the charge, we can apply the superposition principle, which means that we can find the potential due to one of the charges, as if the other were not present.

By symmetry, all four charges are at the same distance from the center, so we can write the total potential, as follows:

V = \frac{k}{d} ( q1 + q2 + q3 + q4) (1)

where d, is the semi-diagonal of the square, that we can find applying Pythagorean theorem, as follows:

d = \sqrt{\frac{L^{2}}{4} + \frac{L^{2}}{4} } = L*\frac{\sqrt{2}}{2}

Replacing by the values in (1) we have:

V = \frac{9e9N*m2/C2}{\frac{L}{2}*\sqrt{2} }* ( +3q -q + 2q + -4q)  = 0 V

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6 0
4 years ago
A 2,200-kg pile driver is used to drive a steel I-beam into the ground. The pile driver falls 3.40 m before coming into contact
love history [14]

Answer:

The magnitude of Force is 8.58×10⁵N and direction is upwards

Explanation:

The work beam does on the pile driver is given by

W=(FCos180°)Δx= -F(0.088m)

From work energy theorem

W_{nc}=(KE_{f}-KE_{i})+(PE_{f}-PE_{i})\\W_{nc}=1/2m(vf^{2}-vi^{2})+mg(yf-yi)

Choosing y=0 at the the level where the driver first contacts the beam and vi=0 at yi=+3.40m and comes to rest again vf=0 at yf= -0.088m

So

-F(0.088m)=1/2m(0-0)+2,200kg(9.81m/s^{2} )(-0.088m-3.40m)\\-F(0.088)=-75508.224\\F=75508.224/0.088\\F=8.58*10^{5} N

The magnitude of Force is 8.58×10⁵N and direction is upwards

6 0
4 years ago
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