The boy’s foot causes the motion. His foot is the one that causes the ball to roll down the hill.
Answer:
Since the net force is to the right (in the direction of the applied force), then the applied force must be greater than the friction force. The friction force can be determined using an understanding of net force as the vector sum of all the forces.
Explanation:
From tables, the speed of sound at 0°C is approximately
V₁ = 331 m/s (in air)
V₃ = 5130 m/s (in iron)
Distance traveled is
d = 100 km = 10⁵ m
Time required to travel in air is
t₁ = d/V₁ = 10⁵/331 = 302.12 s
Time required to travel in iron is
t₂ = d/V₂ = 10⁵/5130 = 19.49 s
The difference in time is
302.12 - 19.49 = 282.63 s
Answer: 283 s (nearest second)
<span>37.8 seconds
First, determine the speed difference between the car and truck.
95 km/h - 75 km/h = 20 km/h
Convert that speed into m/s to make a more convenient unit of measure.
20 km/h * 1000 m/km / 3600 s/h = 5.556 m/s
Now it's simply a matter of dividing the distance between the two vehicles and their relative speed.
210 m / 5.556 m/s = 37.8 s
So it will take 37.8 seconds for the car to catch the truck that's 210 meters in front of the car.</span>
Below are the choices that can be found elsewhere:
a. 268 kJ
<span>b. 271 kJ </span>
<span>c. 9 kJ </span>
<span>d. 6 kJ
</span>
So the key thing to realize here is what the information given to you actually means. Sublimation is going from a sold to a gas. Vaporization is going from a liquid to a gas. Hence you can create two equations from the information that you have:
<span>Ga (s) --> Ga (g) delta H = 277 kJ/mol </span>
<span>Ga (l) --> Ga (g) delta H = 271 kJ/mol </span>
<span>From these two equations, you can then infer how to get the melting equation be simply finding the difference between the sublimation (two steps) and vaporization (one step). </span>
<span>Ga (s) --> Ga (l) delta H = 6 kJ/mol </span>
<span>At this point, all you need to do is a bit of stoichiometry. You start with 1.50 mol and multiply by the amount of energy per mole (6 kJ/mol). </span>
<span>*ANSWER* </span>
<span>9 kJ/mol (C)</span>
