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1 month ago

Person X pushes twice as hard against a stationary brick wall as person Y. Which one of the following statements is correct?

Physics

1 answer:

Keith_Richards [3.2K]1 month ago

6 0

D) Both perform no work

Explanation:

The work accomplished by a force is defined as:

$W=Fd cos \theta$

where

F represents the applied force

d denotes the displacement

is the angle highlighted between the applied force and the displacement vector

$\theta$ From this formula, it is clear that work is only done when displacement occurs, meaning the object has to move.

In this instance, as the wall is unmoving, the displacement is zero: d = 0, thus no work is performed.

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A spring is stretched 6 in by a mass that weighs 8 lb. The mass is attached to a dashpot mechanism that has a damping constant o

Ostrovityanka [3204]

Response:

y= 240/901 cos 2t+ 8/901 sin 2t

Clarification:

To determine mass m=weight/g

m=8/32=0.25

To calculate the spring constant

Kx=mg (with c=6 inches and mg=8 pounds)

K(0.5)=8 (6 inches converts to 0.5 feet)

K=16 lb/ft

The governing equation for the spring-mass system is

my''+Cy'+Ky=F

Inserting the known values yields

0.25 y"+0.25 y'+16 y=4 cos 20 t ----(1) (given C=0.25 lb.s/ft)

Assuming the steady state equation for y is

y=A cos 2t+ B sin 2t

To determine constants A and B, we must equate this with equation 1.

Next, we find y' and y" by differentiating with respect to t.

y'= -2A sin 2t+2B cos 2t

y"=-4A cos 2t-4B sin 2t

Now, substitute the values of y", y' and y into equation 1

0.25 (-4A cos 2t-4B sin 2t)+0.25(-2A sin 2t+2B cos 2t)+16(A cos 2t+ B sin 2t)=4 cos 20 t

By comparing coefficients on both sides

30 A+ B=8

A-30 B=0

From this, we find

A=240/901 and B=8/901

Thus, the steady state response

y= 240/901 cos 2t+ 8/901 sin 2t

6 0

2 months ago

Modern wind turbines generate electricity from wind power. The large, massive blades have a large moment of inertia and carry a

Yuliya22 [3333]

Answer:

Explanation:

a )

Each blade resembles a rod with its axis positioned near one end.

The moment of inertia for one blade is:

= 1/3 x m l²

where m stands for the mass of the blade

l represents the length of each blade.

Total moment of inertia for 3 blades is:

= 3 x $\frac{1}{3}$ x m l²

ml²

2 )

Details provided include:

m = 5500 kg

l = 45 m

Substituting these values produces:

moment of inertia of one blade:

= 1/3 x 5500 x 45 x 45

= 37.125 x 10⁵ kg.m²

Moment of inertia for 3 blades:

= 3 x 37.125 x 10⁵ kg.m²

= 111.375 x 10⁵ kg.m²

c )

Angular momentum

= I x ω

I denotes the moment of inertia of the turbine

ω symbolizes angular velocity

ω = 2π f

f indicates the rotational frequency of the blades

d )

We have I = 111.375 x 10⁵ kg.m² (Calculated)

f = 11 rpm (revolutions per minute)

= 11 / 60 revolutions per second

ω = 2π f

= 2π x 11 / 60 rad / s

Calculating angular momentum yields

= I x ω

111.375 x 10⁵ kg.m² x 2π x 11 / 60 rad / s

= 128.23 x 10⁵ kgm² s⁻¹.

4 0

2 months ago

A helicopter starting on the ground is rising directly into the air at a rate of 25 ft/s. You are running on the ground starting

serg [3582]

Response:

The speed at which the distance from the helicopter to you is changing (in ft/s) after 5 seconds is $\sqrt{725}$ ft/ sec

Clarification:

Provided:

h(t) = 25 ft/sec

x(t) = 10 ft/ sec

h(5) = 25 ft/sec. 5 = 125 ft

x(5) = 10 ft/sec. 5 = 50 ft

At this point, we can determine the distance between the individual and the helicopter utilizing the Pythagorean theorem

$D(t) = \sqrt{h^2 + x^2}$

Now, let's calculate the derivative of distance in relation to time

$\frac{dD}{dt} (t) = \frac{2h \cdot \frac{dh}{dt} +2x \cdot\frac{dx}{dt}} {2\sqrt{h^2 + x^2}}$

By plugging in the values for h(t) and x(t) and simplifying, we arrive at,

$\frac{dD}{dt}(t) = \frac{50t \cdot \frac{dh}{dt} + 20 \cdot \frac{dx}dt}{2\sqrt{625\cdot t^2 + 100 \cdot t^2}}$

$\frac{dh}{dt} = 25ft/sec$

$\frac{dx}{dt} = 10 ft/sec$

$\frac{Dd}{dt} (t) = \frac{1250t +200t}{2\sqrt{725}t}$ = $\frac{725}{\sqrt{725}}$ = $\sqrt{725}$ ft / sec

5 0

1 month ago

A proton moves along the x-axis with vx=1.0×107m/s. As it passes the origin, what are the strength and direction of the magnetic

inna [3103]

Answer:

At this position, the magnetic field equals ZERO

Explanation:

The magnetic field produced by a moving charge is described as

$B = \frac{\mu_0 qv sin\theta}{4\pi r^2}$

Here, we determine the direction of the magnetic field using

$\hat B = \hat v \times \hat r$

Thus, we find

$\hat B = \hat i \times (\hat i + 0\hat j + 0\hat k)$

Leading to a magnetic field of ZERO

Consequently, when the charge moves in the same line as the given position vector, the magnetic field will be nonexistent

3 0

2 months ago

A frictionless inclined plane is 8.0 m long and rests on a wall that is 2.0 m high. How much force is needed to push a block of

serg [3582]

Provided Information:

Length of inclined plane = 8 m

Height of inclined plane = 2 m

Weight of the ice block = 300 N

Required Information:

Force needed to push ice block = F =?

Answer:

Force needed to push the ice block = 75 N

Explanation:

The required force to push this ice block up an inclined plane is given by

F = Wsinθ

where W is the weight of the ice block and θ is the angle indicated in the attached image.

Using trigonometric ratios,

sinθ = opposite/hypotenuse

where the opposite side is the height of the inclined plane and the hypotenuse is the length of the inclined plane.

Thus, sinθ = 2/8

θ = sin⁻¹(2/8)

which leads to θ = 14.48°

Therefore, F = 300*sin(14.48)

results in F = 75 N

This indicates that a force of 75 N is necessary to push the ice block on the specified inclined plane.

7 0

1 month ago