Question 5 of 20 Engineers are using computer models to study train collisions to design safer train cars. They start by modelin
2 answers:
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Answer:
50 lb
Explanation:
Given,
The weight of astronaut's life support backpack on Earth (w) = 300 lb
Acceleration due to gravity on Earth (g) = 9.8 m/s²
Acceleration due to gravity on Moon = g'
We know that weight of an object on Earth is,
Similarly, weight on Moon will be
Thus the astronaut's life support backpack will weigh 50 lb on Moon.
The answer for the following answer is answered below.
- <u><em>Therefore the time period of the wave is 0.01 seconds.</em></u>
- <u><em>Therefore the option for the answer is "B".</em></u>
Explanation:
Frequency (f):
The number of waves that pass a fixed place in a given amount of time.
The SI unit of frequency is Hertz (Hz)
Time period (T):
The time taken for one complete cycle of vibration to pass a given point.
The SI unit of time period is seconds (s)
Given:
frequency (f) = 100 Hz
wavelength (λ) = 2.0 m
To calculate:
Time period (T)
We know;
According to the formula;
<u>f =</u><u></u>
Where,
f represents the frequency
T represents the time period
from the formula;
T =
T =
T = 0.01 seconds
<u><em>Therefore the time period of the wave is 0.01 seconds.</em></u>
(a) 10241 W
In this situation, the car is moving at constant speed: this means that its acceleration along the direction parallel to the slope is zero, and so the net force along this direction is also zero.
The equation of the forces along the parallel direction is:
where
F is the force applied to pull the car
m = 950 kg is the mass of the car
is the acceleration of gravity
is the angle of the incline
Solving for F,
Now we know that the car is moving at constant velocity of
v = 2.20 m/s
So we can find the power done by the motor during the constant speed phase as
(b) 10624 W
The maximum power is provided during the phase of acceleration, because during this phase the force applied is maximum. The acceleration of the car can be found with the equation
where
v = 2.20 m/s is the final velocity
a is the acceleration
u = 0 is the initial velocity
t = 12.0 s is the time
Solving for a,
So now the equation of the forces along the direction parallel to the incline is
And solving for F, we find the maximum force applied by the motor:
The maximum power will be applied when the velocity is maximum, v = 2.20 m/s, and so it is:
(c)
Due to the law of conservation of energy, the total energy transferred out of the motor by work must be equal to the gravitational potential energy gained by the car.
The change in potential energy of the car is:
where
m = 950 kg is the mass
is the acceleration of gravity
is the change in height, which is
where L = 1250 m is the total distance covered.
Substituting, we find the energy transferred: