Answer:
Explanation:
Given
mass of box 
speed of box 
distance moved by the box 
coefficient of kinetic friction 
Friction force 


Kinetic Energy of box will be utilize to overcome friction and rest is stored in spring in the form of elastic potential energy




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Answer:

Explanation:
given,
coefficient of kinetic friction, μ = 0.25
Speed of sled at point A = 8.6 m/s
Speed of sled at point B = 5.4 m/s
time taken to travel from point A to B.
we know,
J = F Δ t
J is the impulse
where F is the frictional force.
t is the time.
we also know that impulse is equal to change in momentum.

frictional force
F = μ N
where as N is the normal force
now,






time taken to move from A to B is equal to 1.31 s
Conduction. Because they are connected as they tranfer energy