Answer:
3 kg
Explanation:
Momentum before = momentum after
m₁u₁ + m₂u₂ = m₁v₁ + m₂v₂
After jumping on the skateboard, the student and the skateboard have the same velocity, so v₁ = v₂.
m₁u₁ + m₂u₂ = (m₁ + m₂) v
(47.4 kg) (4.2 m/s) + m (0 m/s) = (47.4 kg + m) (3.95 m/s)
m = 3 kg
Answer:
a) 
b) 
Explanation:
Let's find the radius of the circumference first. We know that bob follows a circular path of circumference 0.94 m, it means that the perimeter is 0.94 m.
The perimeter of a circunference is:


Now, we need to find the angle of the pendulum from vertical.


Let's apply Newton's second law to find the tension.

We use centripetal acceleration here, because we have a circular motion.
The vertical equation of motion will be:
(1)
The horizontal equation of motion will be:
(2)
a) We can find T usinf the equation (1):

We can find the angular velocity (ω) from the equation (2):

b) We know that the period is T=2π/ω, therefore:

I hope it helps you!
Here, Your Options are absent, but the elements that would most likely become a positive ion will be:
hydrogen, sodium, potassium, lithium, cesium etc.
Hope this helps!