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sergij07 [2.7K]
3 years ago
8

At a construction site, the site manager notices that a crane takes 20 seconds to lift a 500kg steel beam up to a height of 15 m

eters. From this information, he calculates the power output of the crane to be what value?
Physics
1 answer:
posledela3 years ago
5 0
The work done is equal to the change in potential energy which is:
P.E = mgh
P.E = 500 x 9.81 x 15
P.E = 73,575 J

Power = work / time
Power = 73,575 / 20
Power = 3,700 Watts
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a particle of mass m sits at rest at x = 0. At time t = 0 a force given by F = Fe^(-t/T) is applied in the +x direction; F and T
wlad13 [49]

Explanation:

Given:F=m\ddot{x}=Fe^{-\frac{t}{T}}

Solving for \ddot{x}:

\ddot{x}=\frac{F}{m}e^{-\sqrt{\frac{F}{m} } t}

where:

T=\sqrt{\frac{m}{F}}

Integrating to get \dot{x} with initial conditions \dot{x}(0)=0:

\dot{x}=\sqrt{\frac{F}{m}}-\sqrt{\frac{F}{m}} e^{-\sqrt{\frac{F}{m}} t}

Integrating to get x with initial conditions x(0) = 0:

x=-1+\sqrt{\frac{F}{m}} t+e^{-\sqrt{\frac{F}{m}}t}

When t=T:

x=-1+\sqrt{\frac{F}{m}}\sqrt{\frac{m}{F}}+e^{-\sqrt{\frac{F}{m}}\sqrt{\frac{m}{F}}}=\frac{1}{e}

\dot{x}=\sqrt{\frac{F}{m}}-\sqrt{\frac{F}{m}} e^{-\sqrt{\frac{F}{m}}\sqrt{\frac{m}{F}}}=\sqrt{\frac{F}{m}}(1-\frac{1}{e})

4 0
3 years ago
A man attempts to push a 19.8 kg crate across a warehouse floor. He slowly increases the force until the crate starts to move at
VARVARA [1.3K]

Answer:

 μ = 0.18

Explanation:

Let's use Newton's second Law, the coordinate system is horizontal and vertical

Before starting to move the box

Y axis

     N-W = 0

     N = W = mg

X axis

     F -fr = 0

     F = fr

The friction force has the formula

     fr = μ N

     fr =  μ m g

At the limit point just before starting the movement

     F = μ m g

     μ = F / m g

calculate

      μ = 34.8 / (19.8 9.8)

    μ = 0.18

7 0
3 years ago
Read 2 more answers
________ capture solar energy and use photosynthesis to produce sugars.
vovikov84 [41]

Answer:

Option (A)

Explanation:

The green plants are capable of synthesizing their own food, in the presence of sunlight, CO₂ and water, and in return, liberates food and oxygen (O₂). This process is known as photosynthesis. This process is possible due to the presence of chlorophyll pigments on the plant leaves.

These green plants are also known as producers, because they are able to generate food for the consumers.

Thus, the correct answer is option (A).

8 0
3 years ago
the car starts from a stop to travel 1100 meters in 14 seconds. it is clocked at 65 m/s at point k. find its average speed and a
inysia [295]

Answer:

The average velocity of the car is, V = 74.04 m/s

Explanation:

Given data,

The initial velocity of the car, u = 0 m/s

The displacement of the ca, S = 1100 m

The time period of travel, t = 14 s

The velocity of the car at point k, v = 65 m/s

Using the II equation of motion,

                      S = ut + ½  at²

Substituting the given values,

                      1100 = 0 + ½ x a x 14²

                          a = 11.22 m/s²

Using the III equation of motion

                         v² = u² + 2 as

                          v = √(2as)              (∵ u = 0)

Substituting,

                           v = √(2 x 11.22 x 1100)

                              = 157.11 m/s

The average speed of the car,

                        V=\frac{0+65+157.11}{3}

                        V = 74.04 m/s

Hence, the average velocity of the car is, V = 74.04 m/s

4 0
3 years ago
Explique ¿por que un objeto que tiene energía es capaz de realizar un trabajo?
Nana76 [90]
By striking another object that is free to move, the moving object can exert a force and cause the second object to shift its position. While the object is moving, it has the capacity for doing work. Energy means the ability to do work, so all moving things have energy by virtue of their motion.




Translation: Al golpear otro objeto que se puede mover libremente, el objeto en movimiento puede ejercer una fuerza y ​​hacer que el segundo objeto cambie de posición. Mientras el objeto se mueve, tiene la capacidad de realizar un trabajo. Energía significa la capacidad de realizar un trabajo, por lo que todas las cosas en movimiento tienen energía en virtud de su movimiento.

3 0
2 years ago
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