The speed 
of the elevator at the beginning of the 8 m descent is nearly 4 m/s. Hence, option A is the correct answer.
We are given that-
the mass of the elevator (m) = 1000 kg ;
the distance the elevator decelerated to be y = 8m ;
the tension is T = 11000 N;
let us determine the acceleration 'a' by using Newton's second law of motion.
∑Fy = ma
W - T = ma
(1000kg x 9.8 m/s² ) - 11000N = 1000 kg x a
9800 - 11000 = 1000
a = - 1.2 m/s²
Using the equation of kinematics to determine the initial velocity.
² = ² + 2ay
= √ ( 2 x 1.2m/s² x 8 m )
= √19.2 m²/s²
= 4.38 m/s ≈ 4 m/s
Hence, the initial velocity of the elevator is 4m/s.
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Answer:1.301 s
Explanation:
Given
Initial Velocity(u)=30 m/s
Height of cliff=8.3 m
Time taken to cover 8.3 m
here Initial vertical velocity is 0
Horizontal distance
Answer: 250n
Explanation:
The formula for gravitational force is: F = (gMm)/r^2
There are two factors at play here:
1) The mass of the planet 'M'
2) The radius 'r'
We can ignore the small M and the g, they are constants that do not alter the outcome of this question.
You can see that both M and r are double that of earth. So lets say earth has M=1 and r=1. Then, new planet would have M=2 and r=2. Let's sub these two sets into the equation:
Earth. F = M/r^2 = 1/1
New planet. F = M/r^2 = 2/4 = 1/2
So you can see that the force on the new planet is half of that felt on Earth.
The question tells us that the force on earth is 500n for this person, so then on the new planet it would be half! So, 250n!
The potential energy of the skateboarder at the top of the ramp is
489.1 J.
<h3>Is kinetic energy always equal to potential energy?</h3>
The amount of kinetic energy change and the amount of potential energy change are equal in all physical processes that take place in closed systems. When the kinetic energy rises, the potential energy falls, and vice versa.
Potential energy is the stored energy in any object or system as a result of its position or component arrangement. However, external factors like air or height have no effect on it. The energy of a moving object or system is referred to as kinetic energy.
Potential energy = kinetic energy
Potential energy = 1/2mv²
Potential energy = 1/2 × 67×7.3
Potential energy = 489.1 J.
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Answer:
4.6 kHz
Explanation:
The formula for the Doppler effect allows us to find the frequency of the reflected wave:
where
f is the original frequency of the sound
v is the speed of sound
vs is the speed of the wave source
In this problem, we have
f = 41.2 kHz
v = 330 m/s
vs = 33.0 m/s
Therefore, if we substitute in the equation we find the frequency of the reflected wave:
And the frequency of the beats is equal to the difference between the frequency of the reflected wave and the original frequency:
