The final velocity of the skater is 2.34 m/s forward
Explanation:
We can solve this problem by using the law of conservation of momentum. In fact, the total momentum of the system before and after the ball is thrown must be conserved, in absence of external forces.
Before the ball is thrown, the total momentum is:
where
M = 61 kg is the mass of the skater
m = 4.0 kg is the mass of the ball
u = 2.5 m/s (forward) is the combined velocity of the skater and the ball
After, the ball is thrown at twice the velocity, so the final total momentum is
where
V is the final velocity of the skater
v = 2(2.5) = 5.0 is the final velocity of the ball
Since the total momentum must be conserved, we can write
So, the skater is moving at 2.34 m/s (forward) after the shot.
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Answer:
Tension, T = 0.0115 N
Explanation:
Given that,
Mass of the plastic ball, m = 1.1 g
Length of the string, l = 56 cm
A charged rod brought near the ball exerts a horizontal electrical force F on it, causing the ball to swing out to a 21.0 degree angle and remain there. According to attached figure :
T is tension in the string
So, the tension in the string is 0.0115 N.
Answer:
Her angular speed (in rev/s) when her arms and one leg open outward is
Explanation:
Initial moment of inertia when arms and legs in is
Final moment of inertia when her arms and on leg open outward,
Initial angular speed
Let the final angular speed be
Since external torque on her is zero so we can apply conservation of angular momentum
=>
=>
Thus her angular speed (in rev/s) when her arms and one leg open outward is