Answer:
D. The air we breathe is a homogeneous mixture because it has substances but the same appearance throughout.
Explanation:
The air we breathe is a homogeneous mixture.
Air is a mixture of many gases. A homogeneous mixture is one whose constituents exists in one phase.
Air is a gas - gas mixtures.
A mixture has indefinite composition. They consist of two or more elements and or compounds in any proportion by mass.
Constituents retain their identities i.e. physical properties are retained.
Acceleration= v/ r
So you have to divide 700 by 0.800 which is equal to 875 m/s 2
Answer:
a. 120 W
b. 28.8 N
Explanation:
To a good approximate, the only external force that does work on a cyclist moving on level ground is the force of air resistance. Suppose a cyclist is traveling at 15 km/h on level ground. Assume he is using 480 W of metabolic power.
a. Estimate the amount of power he uses for forward motion.
b. How much force must he exert to overcome the force of air resistance?
(a)
He is 25% efficient, therefore the cyclist will be expending 25% of his power to drive the bicycle forward
Power = efficiency X metabolic power
= 0.25 X 480
= 120 W
(b)
power if force times the velocity
P = Fv
convert 15 km/h to m/s
v = 15 kmph = 4.166 m/s
F = P/v
= 120/4.166
= 28.8 N
definition of terms
power is the rate at which work is done
force is that which changes a body's state of rest or uniform motion in a straight line
velocity is the change in displacement per unit time.
You can deal with this question using the collision theory, which states that the chemical reactions occur when particles collide with enough energy to reach the Activation Energy.
The velocity of the particles is related with the temperature. At higher temperatures, higher velocities and higher frequency of collisions.
Also, at higher concentration (more particles is a same volume) the number of collisions will increase.
Then, hIgher concentration and higher temperature will increase the frequency of the molecular collisions..
Then, the answer is the proposal #1: "<span>increasing the frequency of molecular collisions"</span>
