Answer: D. decreasing the temperature
Explanation:
Answer:
Democritus had no scientific instruments to extend the reach of his senses, so all of his experiments were just 'mind experiments', but because Democritus was a philosopher, he thought more into depth about why we humans are alive which led to the atomic theory.
Explanation:
The answer to this question is A.
Answer:
Halfway between B and A on the return leg.
Explanation:
Your average SPEED for the entire trip will equal your constant speed as the time and distance increase at proportionate rates.
Your average VELOCITY will equal your constant speed while you travel from A to B because time and displacement are increasing at proportionate rates.
When you turn around at B to return, your Displacement is now decreasing while your travel time continues to increase, so your average velocity decreases.
Lets say the distance from A to B is 90 km and your constant speed is 30 km/hr.
your average speed is 30 km/hr because you took 6 hrs to travel 180 km
We want to find your position when your average velocity is 30/3 = 10 km/hr
it took 3 hrs to go 90 km from A to B. Let t be the time lapsed since turn around
your displacement is given by d = 90 - 30(t)
and your total time of travel is t + 3 hrs
v = d/t
10 = (90 - 30t) / (t + 3)
10(t + 3) = (90 - 30t)
10t + 30 = 90 - 30t
40t = 60
t = 1.5 hrs
This will occur when you are halfway between B and A
Answer:
a) P = 807.85 N, b) P = 392.15 N, c) P = 444.12 N
Explanation:
For this exercise, let's use Newton's second law, let's set a reference frame with the x-axis parallel to the plane and the direction rising as positive, and the y-axis perpendicular to the plane.
Let's use trigonometry to break down the weight
sin θ = Wₓ / W
cos θ = W_y / W
Wₓ = W sin θ
W_y = W cos θ
Wₓ = 1200 sin 30 = 600 N
W_y = 1200 cos 30 = 1039.23 N
Y axis
N- W_y = 0
N = W_y = 1039.23 N
Remember that the friction force always opposes the movement
a) in this case, the system will begin to move upwards, which is why friction is static
P -Wₓ -fr = 0
P = Wₓ + fr
as the system is moving the friction coefficient is dynamic
fr = μ N
fr = 0.20 1039.23
fr = 207.85 N
we substitute
P = 600+ 207.85
P = 807.85 N
b) to avoid downward movement implies that the system is stopped, therefore the friction coefficient is static
P + fr -Wx = 0
fr = μ N
fr = 0.20 1039.23
fr = 207.85 N
we substitute
P = Wₓ -fr
P = 600 - 207,846
P = 392.15 N
c) as the movement is continuous, the friction coefficient is dynamic
P - Wₓ + fr = 0
P = Wₓ - fr
fr = 0.15 1039.23
fr = 155.88 N
P = 600 - 155.88
P = 444.12 N
