Answer: Physical changes only change the appearance of a substance, not its chemical composition. Chemical changes cause a substance to change into an entirely substance with a new chemical formula. Chemical changes are also known as chemical reactions.
Explanation:
Answer:
416.667 m/s
Explanation:
divide the distance by the time
Answer:
v = 9.04 m / s
Explanation:
For this exercise we can use the relation that the work of the non-conservative force (friction) is equal to the variation of the mechanical energy of the system.
W = Em_f - Em₀ (1)
Starting point. Lower slope
Em₀ = K = ½ m v²
highest point. Where is the skier at a height h
Em_f = U = m g h
The work of rubbing
W = -fr x
the negative sign is because the friction force opposes the movement.
Let's set a reference system where the x axis is parallel to the slope and the y axis is perpendicular
let's use trigonometry to break down the weight
cos θ = W_y / W
sin θ = Wₓ / W
W_y = W cos θ
Wₓ = W sin θ
Y axis
N - Wₓ = 0
N = mg sin θ
X axis
fr = m a
the friction force has the expression
fr = μ N
fr = μ mg sin θ
we look for the job
W = - μ mg sin θ x
where x is the distance along the slope
we substitute in 1
-μ mg sin θ x = mg h - ½ m v²
let's use trigonometry to find the distance x
tan 30 = h / x
x = h / tan 30
we substitute
- 
= m gh - ½ m v²
we use
tan 30 = sin30 / cos30
v² = 2g h + 2 μ g h cos 30
v = 
let's calculate
v = 
v = 9.04 m / s
Answer:
once the parachute is opened, the air resistance overwhelms the downward force of gravity. The net force and the acceleration on the falling skydiver is upward. ... The skydiver thus slows down. As the speed decreases, the amount of air resistance also decreases until once more the skydiver reaches a terminal velocity.
Explanation:
Answer:
Sharpening a knife reduces it's height as a wedge thus giving it more efficiency.
Explanation:
Mechanical advantage refers to the degree or quantity to which a force is increased or amplified by using a tool or a machine.
Mechanical Advantage can be calculated as follows:
Lenght of Incline (LI) / Height of Incline (HI)
Assume I have constructed a hedge with an inclination that run 10 meters from point x to point y (which is the back of a truck. Point y to the floor is 5 meters.
If LI = 10m and
HI= 5m
The mechanical advantage is given as 10/5 = 2
The angle of incline is also called the effort distance. From our calculations above, by sacrificing horizontal movement, I reduced the amount of effort it would have cost to lift up that object from ground up - a distance of 5 meters.
Think of a knife as a form of a similar wedge.
The more a knife is sharpening of a knife further reduces its angle of elevation. Thats why it becomes more efficient to use, hence our mechanical advantage.
Cheers
