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Kitty [74]
3 years ago
13

In a day, an electrical resistance heater uses 10 kW-h of electricity. In the same day, the heater delivers 9 kW-h of heat to th

e house in which it is located. Is this possible or is this a perpetual motion machine? If so, what kind? Explain your reasoning. (5 points)
Physics
1 answer:
Illusion [34]3 years ago
4 0

Answer:

The heater is not a perpetual motion machine.

Explanation:

A perpetual motion machine is a machine that can run forever without any energy inputs. That is, it delivers the same amount of energy as it uses. Such a machine is almost hypothetical because it is opposite to the second law of thermodynamics.

The heater mentioned in the question is not a perpetual motion machine because it delivers less energy than it requires. It uses 10 kW-h of electricity to produce 9 kW-h of heat according to the question.

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A small boat is moving at a velocity of 3.35m/s when it is accelerated by a river current perpendicular to the initial direction
mr_godi [17]

Answer:

 v =7.1 m/s

Explanation:

Given that

u = 3.35 m/s

t= 5 s

a= 0.75 m/s²

The final velocity = v

We know v = u +at

v=final velocity

u=initial velocity

Now by putting the values in the above equation

v = 3.35 + 0.75 x 5 m/s

v =7.1 m/s

Therefore the final velocity will be 7.1 m/s

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3 years ago
Which of these statements is correct about photosynthesis and decomposition?
Ede4ka [16]
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Most energy obtained from water is converted from _____.
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Potential energy behind dams
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A block is attached to a spring, with spring constant k, which is attached to a wall. it is initially moved to the left a distan
Ghella [55]

Answer:

x(t) = d*cos ( wt )

w = √(k/m)

Explanation:

Given:-

- The mass of block = m

- The spring constant = k

- The initial displacement = xi = d

Find:-

- The expression for displacement (x) as function of time (t).

Solution:-

- Consider the block as system which is initially displaced with amount (x = d) to left and then released from rest over a frictionless surface and undergoes SHM. There is only one force acting on the block i.e restoring force of the spring F = -kx in opposite direction to the motion.

- We apply the Newton's equation of motion in horizontal direction.

                             F = ma

                             -kx = ma

                             -kx = mx''

                              mx'' + kx = 0

- Solve the Auxiliary equation for the ODE above:

                              ms^2 + k = 0

                              s^2 + (k/m) = 0

                              s = +/- √(k/m) i = +/- w i

- The complementary solution for complex roots is:

                              x(t) = [ A*cos ( wt ) + B*sin ( wt ) ]

- The given initial conditions are:

                              x(0) = d

                              d = [ A*cos ( 0 ) + B*sin ( 0 ) ]

                              d = A

                              x'(0) = 0

                              x'(t) = -Aw*sin (wt) + Bw*cos(wt)

                              0 = -Aw*sin (0) + Bw*cos(0)

                              B = 0

- The required displacement-time relationship for SHM:

                               x(t) = d*cos ( wt )

                               w = √(k/m)

3 0
3 years ago
What is the name of the kind of stretch that involves stretching as far as you can and then holding for 10-30 seconds
Dmitriy789 [7]

Answer:

Static stretching.

Explanation:

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7 0
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