A parent swings a 13.5 kg child
1 answer:
The speed of the child is 2.21 m/s
Explanation:
The child is moving in circular motion. First of all, we find its frequency of revolution, which is given by:
where
N = 11 is the number of revolutions
t = 25.4 s is the time elapsed
So,
Now we find the angular frequency, which is given by
And now we can fidn the linear speed of the child, which is given by
where
is the angular frequency
r = 0.811 m is the radius of the circular trajectory
Substituting,
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Answer:
a) 3.43 m/s
Explanation:
Due to the law of conservation of momentum, the total momentum of the bullet - rifle system must be conserved.
The total momentum before the bullet is shot is zero, because they are both at rest, so:
Instead the total momentum of the system after the shot is:
where:
m = 0.006 kg is the mass of the bullet
M = 1.4 kg is the mass of the rifle
v = 800 m/s is the velocity of the bullet
V is the recoil velocity of the rifle
The total momentum is conserved, therefore we can write:
Which means:
Solving for V, we can find the recoil velocity of the rifle:
where the negative sign indicates that the velocity is opposite to direction of the bullet: so the recoil speed is
a) 3.43 m/s