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uysha [10]
3 years ago
9

A 200. Kg load of bricks is to be lifted from the ground to the top of a 30.0 m high building in 30.0 s. If a 75.0 N frictional

force in the pulley opposes motion, what minimum power motor would be needed?
Physics
1 answer:
coldgirl [10]3 years ago
3 0

Answer:

The minimum power the motor would need is 2035 Watts.

Explanation:

the minimum power motor needed is given by the total work done on the load, Wtot and the total time it takes the load to be lifted, given by:

P = Wtot/t

the forces doing works on the load is the gravitational force, Wfg and the frictional force, Wf the total work done on the load is:

Wtot = Wfg + Wf

        =  m×g×d + f×d

        = d×(m×g + f)

        = (30)×(200×9.8 + 75)

         = 61050 J

it takes t = 30s for the load to be lifted high the building, the minimum power neeed is then:

P = Wtot/t

  = (61050)/(30)

  = 2035 Watts

Therefore, the minimum power the motor would need is 2035 Watts.

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assume the suns total energy output is 4.0 * 10^26 watts, and 1 watt is 1 joule/second. assume 4.3 * 10^-12 J is released from e
Dmitry [639]

Answer:

9.3\cdot 10^{37}

Explanation:

Power is defined as the energy produced (E) per unit of time (t):

P= \frac{E}{t}

This means that the energy produced in the Sun each second (1 s), given the power P=4.0\cdot 10^{26}W, is

E=Pt=(4.0\cdot 10^{26}W)(1s )=4.0\cdot 10^{26} J

Each p-p chain reaction produces an amount of energy of

E_1 = 4.3\cdot 10^{-12} J

in order to get the total number of p-p chain reactions per second, we need to divide the total energy produced per second by the energy produced by each reaction:

n=\frac{E}{E_1}=\frac{4.0\cdot 10^{26} J}{4.3\cdot 10^{-12} J}=9.3\cdot 10^{37}

3 0
3 years ago
Suppose an electrical wire is replaced with one having every linear dimension doubled (i.e. the length and radius have twice the
saul85 [17]

Answer:

The wire now has less (the half resistance) than before.

Explanation:

The resistance in a wire is calculated as:

R=\alpha \frac{l}{s}

Were:

R is resistance

\alpha is the resistance coefficient

l is the length of the material

s is the area of the transversal wire, in the case of wire will be circular area (s=\pi r^{2}).

So if the lenght and radius are doubled, the equation goes as follows:

R=\alpha \frac{l}{\pi r^{2} } =\alpha \frac{2l}{\pi {(2r)}^{2} } =\alpha \frac{2l}{\pi 4 {r}^{2} }=\frac{1}{2} \alpha \frac{l}{\pi r^{2} }

So finally because the circular area is a square function, the resulting equation is half of the one before.

7 0
3 years ago
A constant force of 5.00 N acts on a 2.50 kg object for 10.0 s. What are the changes in the object’s momentum and velocity?
dimulka [17.4K]
Hope this answer helps, cause Idk, I might be wrong, but I still, I used the correct formulas, so I might be correct

7 0
3 years ago
The launch speed of a projectile is three times the speed it has at its maximum height.what is the elevation angle at launch?
Sphinxa [80]

Answer:

Given: a projectile of initial launch velocity(V) and launch angle ∅ and no air resistance. At the maximum height, the projectile would have a zero contribution of speed from the vertical component(Vy) Therefore, if we say Vx=Vcos∅ is the only speed the projectile has at the instant of maximum height then we can replace Vx with 1/5V and write 1/5V=Vcos∅. Solving for the the launch angle ∅, gives Inverse Cos(1/5)=78.5 degrees.

6 0
2 years ago
A student throws a water balloon with speed v0 from a height h = 1.82 m at an angle θ = 29° above the horizontal toward a target
3241004551 [841]

Answer:

v_o = 7.76 m/s

Explanation:

As we projected the balloon at speed vo at an angle of 29 degree

so the two component of velocity is given as

v_x = v_ocos29 = 0.875 v_o

v_y = v_o sin29 = 0.485 v_o

now we know that in x direction we have

d = v_x t

7.5 = 0.875 v_o t

v_o t = 8.57

in y direction we have

- 1.82 = (0.485 v_o) t - \frac{1}{2}gt^2

-1.82 = 0.485(8.57) - 4.9 t^2

t = 1.1 s

now we have

v_o = 7.76 m/s

7 0
3 years ago
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