Answer:
f=ma.......m=f/a......m=20kg
Have you ever been in a bus, a train, or a car ?
What happens to you when it stops suddenly ?
A body in motion continues in motion unless
an external force acts on it and makes it stop.
Amy's body keeps moving forward when the train stops.
She pitches forward, and if she doesn't reach out and grab
a seat or a seated person, she may lose her footing and fall
on her face.
Choice - 'A' is a very good explanation.
The other choices aren't.
'C' is a good hunch, but it only applies to her feet.
The rest of her keeps going.
'D' is nonsense. There are no mysterious forces of
'repulsion' or 'attraction' on the train.
Answer:
a useful sporting analogy ... Teachers of science routinely use analogies to help ... balls over the bar and you will probably find that.
Answer:
ρ_body = 1000 kg / m³
Explanation:
This is an exercise in fluid mechanics, specifically we must use the Archimedean principle, which states that the thrust is equal to the weight of the dislodged liquid.
In this case let's start by finding the volume of our body
oak block
v = l to h
v = 0.02 0.02 0.05
V = 2 10⁻⁵ m³
cooper block indicate that it has the same dimensions so its volume is the same, the total volume of the body is
V_total = 4 10⁻⁵ m³
as they indicate that the body is fully submerged there is a balance between weight and thrust
B - W = 0
the push is
B = ρ_fluid g V_total
the body weight is
ρ_body = M / V_total
M = ρ_body V_total
W = Mg
W = ρ_body V_total g
we substitute
ρ_fluid g V_total = ρ_body V_total g
ρ_body = ρ_fluid
in this case the body is in equilibrium in the fluid, in case the density of the body is greater than that of the fluid, the body sinks
Therefore the average density is equal to the density of the fluid, since since it is water the density is
ρ_body = 1000 kg / m³
