The same physics student jumps off the back of her Laser again, but this time the Laser is
2 answers:
a) The speed of the student after the jump is 1.07 m/s
b) The final speed of the laser is 10.4 m/s
Explanation:
a)
We can solve this problem by applying the law of conservation of momentum: if there are no external forces acting on the system, the total momentum of the student+Laser system must be constant. Therefore, we can write:
where
The initial momentum is zero
m = 42 kg is the mass of the Laser
v = 1.5 m/s is the final velocity of the Laser
M = 59 kg is the mass of the student
V is the final velocity of the student
Solving the equation for V, we find the velocity of the student:
So, the final speed of the student is 1.07 m/s.
b)
In this case, the laser and the student are travelling at 3.1 m/s before the student jumps off: therefore, the total momentum before the jump is not zero.
So, the equation of the conservation of momentum is
where
m = 42 kg is the mass of the Laser
M = 59 kg is the student's mass
u = 3.1 m/s is the initial velocity of the student and the Laser
V = -2.1 m/s is the velocity of the student after the jump (she jumps backward)
v is the final velocity of the Laser
And solving for v, we find
Learn more about momentum:
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Answer:
The distribution is as depicted in the attached figure.
Explanation:
From the given data
- The plane wall is initially with constant properties is initially at a uniform temperature, To.
- Suddenly the surface x=L is exposed to convection process such that T∞>To.
- The other surface x=0 is maintained at To
- Uniform volumetric heating q' such that the steady state temperature exceeds T∞.
Assumptions which are valid are
- There is only conduction in 1-D.
- The system bears constant properties.
- The volumetric heat generation is uniform
From the given data, the condition are as follows
<u>Initial Condition</u>
At t≤0
This indicates that initially the temperature distribution was independent of x and is indicated as a straight line.
<u>Boundary Conditions</u>
<u>At x=0</u>
<u /><u />
This indicates that the temperature on the x=0 plane will be equal to To which will rise further due to the volumetric heat generation.
<u>At x=L</u>
<u /><u />
This indicates that at the time t, the rate of conduction and the rate of convection will be equal at x=L.
The temperature distribution along with the schematics are given in the attached figure.
Further the heat flux is inferred from the temperature distribution using the Fourier law and is also as in the attached figure.
It is important to note that as T(x,∞)>T∞ and T∞>To thus the heat on both the boundaries will flow away from the wall.
