Where are the statements? You forgot to attach them lol
You're only asking 5 points for this question? it's kinda a lot :) just saying (i'm calculating it right now i'll comment the right answers)
Answer:
a) W = 180.87 J
, b) ΔU = -180.87 J
, c) ΔU = -180.87 J
Explanation:
a) Work is defined as
W = F .ds
Where bold indicates vectors, we can write the scalar product
W = F s cos θ
Where the angle is between force and displacement.
The force of gravity is the weight of the body, which is directed downwards and the displacement thickens the tip of the cliff at the bottom, so that it is directed downwards, therefore the angle is zero degrees
W = y
W = m g y
For this problem we must fix a reference system, from the statement it is established that the system is placed at the base of the cliff, so that final height is zero and the initial height (y₀ = 7.69m)
W = 2.40 9.8 (7.69-0)
W = 180.87 J
b) The potential energy is
U = mg y
The change in potential energy,
ΔU = - U₀
ΔU = mg (- y₀)
ΔU = 2.4 9.8 (0 -7.69)
ΔU = -180.87 J
c) in this case we change the reference system to the height of the cliffs, for this configuration
y₀ = 0
= -7.69 m
ΔU = 2.4 9.8 (-7.69 -0)
ΔU = -180.87 J
Answer:
The height in which the book is dropped from is 1.28 m.
Explanation:
Mass of the book, m = 1.5 kg
initial velocity of the book, u = 0
final velocity of the bok, v = 5 m/s
The height in which the book is dropped from is given by;
v² = u² + 2gh
v² = 0 + 2gh
v² = 2gh
h = v² / 2g
h = (5)² / (2 x 9.8)
h = 1.28 m
Therefore, the height in which the book is dropped from is 1.28 m.
Answer: e. 37
Explanation:
When two vectors are added, the maximum and minimum posible values, happen when both vectors are aligned each other.
If both vectors aim in the same direction, the maximum value is just the arithmetic sum of their lengths, in this case, 60.
If they aim in opposite direction, the resultant is the substraction of their magnitudes, which yields 20.
Any other posible value (depending on the angle between vectors, which can span from 0º to 180º) must be between those values.
So, the only choice that fits within this interval, is 37.