I think it's 3. within an outer arm
Remember the rule of thumb that every person learns in Elementary Science? You must do multiple experiments in order to get to a conclusion. In order for a conclusion to be valid you must test the conclusion multiple times. You wouldn't want a doctor to just test an aspirin 1 time on 1 patient and say yes it works correct? No, you would want him/her to test on multiple patients in multiple settings and conditions so that when you take an aspirin you know that it will work for what you are taking it for. So ..... with all that being said.....Your answer is (A). The results are more likely to have errors.
Answer:
v = ((m + M) / m)*√(2*g*h)
Explanation:
Given
m = mass of the projectile
M = mass of the ballistic pendulum
v = initial speed of the projectile
v' = speedof the system (pendulum + projectile) after the inelastic collision
h = maximum height reached for the system
Knowing that is an inelastic collision we have
m*v + M*(0) = (m+M)*v'
⇒ v' = m*v / (m+M)
After the collision, we apply the Principle of the Conservation of Energy
Ki + Ui = Kf + Uf
where
Ui = Kf = 0 J
then
Ki = Uf
0.5*(m+M)*v'² = (m+M)*g*h
⇒ 0.5*v'² = g*h
⇒ v'² = 2*g*h
⇒ (m*v / (m+M))² = 2*g*h
⇒ v = ((m+M) / m)*√(2*g*h)
