Answer:
vB = 15.4 m/s
Explanation:
Principle of conservation of energy:
Because there is no friction the mechanical energy is conserve
ΔE = 0
ΔE : mechanical energy change (J)
K : Kinetic energy (J)
U: Potential energy (J)
K = (1/2)mv²
U = m*g*h
Where :
m: mass (kg)
v : speed (m/s)
h : hight (m)
Ef - Ei = 0
(K+U)final - (K+U)initial =0
(K+U)final = (K+U)initial
((1/2)mv²+m*g*h)final = ((1/2)mv²+m*g*h)initial , We divided by m both sides of the equation:
((1/2)vB² + g*hB = (1/2 )vA²+ g*hA
(1/2) (vB)² + (9.8)*(14.7) = 0 + (9.8)(26.8 )
(1/2) (vB)² = (9.8)(26.8 ) - (9.8)*(14.7)
(vB)² = (2)(9.8)(26.8 - 14.7)
(vB)² = 237.16

vB = 15.4 m/s : speed of the cart at B
C. 5
a neutral atom has no electrical charge. protons are positive and electrons are negative, they need to be the same to make it a neutral atom.
If two object experiences the same displacement at the same time, the two objects must have the same average velocity.
The average velocity of an object is defined as the change in displacement per change in time of motion. This can be written as follows;

If two object experiences the same displacement at the same time, it means that the change in displacement with time is constant.

Thus, we can conclude that if two object experiences the same displacement at the same time, the two objects must have the same average velocity.
Learn more here: brainly.com/question/23856383