Would water, steam, granite, or lead make the best thermal insulator? A thermal insulator is a substance that requires a lot of
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Answer:
1)) ΔU = -8.96 J, 2) k = 8.18 10⁴ N / m, 3) v = 8.47 m / s
Explanation:
For this exercise we will use conservation of energy.
Starting point. Point where the pineapple comes out
Em₀ = U = m g h
where the reference frame is placed on the ground
Final point. Point where pineapple stops
Em_f = K_e + U = ½ k y² + m g y
1) the change in gravitational potential energy is
ΔU = U_f - U₀
ΔU = m g y - m g h
ΔU = mg (y-h)
let's calculate
ΔU = 0.116 9.8 (0.0148 - 7.9)
ΔU = -8.96 J
The negative sign indicates that the energy decreases
2) let's use energy conservation
Em₀ = Em_f
mg h = ½ k y² + mg y
k = mg (h-y)
let's calculate
k = 0.116 9.8 (7.9 - 0.0148)
k = 8.18 10⁴ N / m
3) we use the same starting point and as the end point we use this height (y₂ = 4.24 m)
Em_{f2} = K + U = ½ m v² + mg y₂
energy is conserved
Em₀ = Em_{f2}
mgh = ½ m v² + m g y₂
v =
let's calculate
v =
v = 8.47 m / s