For this case we first think that the skateboard and the child are one body.
We have then:
1 = jug
2 = skateboard + boy
By conservation of the linear amount of movement:
M1V1i + M2V2i = M1V1f + M2V2f
Initial rest:
v1i = v2i = 0
0 = M1V1f + M2V2f
Substituting values
0 = (7.8) (3.2) + (M2) (- 0.65)
0 = 24.96 + M2 (-0.65)
-24.96 = (-0.65) M2
M2 = (-24.96) / (- 0.65) = 38.4 kg
Then, the child's mass is:
M2 = Mskateboard + Mb
Clearing:
Mb = M2-Mskateboard
Mb = 38.4 - 1.9
Mb = 36.5 Kg
answer:
the boy's mass is 36.5 Kg
Answer:
Part a)

Part b)

Part c)

Explanation:
Part a)
As we know that force on the passenger while moving in circle is given as

now variation in force is given as

here speed is constant
Part b)
Now if the variation in force is required such that r is constant then we will have

so we have

Part c)
As we know that time period of the circular motion is given as

so here if radius is constant then variation in time period is given as

The way it rotates is Counter-clockwise
Answer:
encontré esto fuera de google, "Estos conceptos físicos que parecen necesarios en cualquier teoría física suficientemente amplia son los llamados conceptos físicos fundamentales, una lista no exhaustiva de los mismos podría ser: espacio, tiempo, energía, masa, carga eléctrica, etc."
espero que esto ayude, que tengas un gran día, Y mantente segura! :) :D :3