A 7.91g bullet is fired into a 1.52-kg ballistic pendulum initially at rest and becomes embedded in it. The pendulum subsequentl
1 answer:
Answer:
D
Explanation:
By law of conservation of momentum:
momentum before collision = momentum after collision
Initial speed of bullet is unknown whereas initial speed of pendulum will be zero as it was at rest.
Final speed of bullet and pendulum will be equal as bullet is embedded in pendulum and both moves together a vertical distance of 6.89cm.
Using third equation of motion:
where:
Thus by placing values
this speed will be final speed of collision for the calculation of initial speed of bullet.
Putting values:
This 224m/s = 0.224Km/s which is closest to D
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Answer:
The horizontal distance is 4.823 m
Solution:
As per the question:
Mass of man, m = 65.0 kg
Height of the hill, H = 5.00 m
Mass of the backpack, m' = 20.0 kg
Height of ledge, h = 2 m
Now,
To calculate the horizontal distance from the edge of the ledge:
Making use of the principle of conservation of energy both at the top and bottom of the hill (frictionless), the total mechanical energy will remain conserved.
Now,
where
KE = Kinetic energy
PE = Potential energy
Initially, the man starts, form rest thus the velocity at start will be zero and hence the initial Kinetic energy will also be zero.
Also, the initial potential energy will be converted into the kinetic energy thus the final potential energy will be zero.
Therefore,
where
v = velocity at the hill's bottom
Now,
Making use of the principle of conservation of momentum in order to calculate the velocity after the inclusion, v' of the backpack:
Now, time taken for the fall:
Now, the horizontal distance is given by:
x = v't =