A champion athlete can produce one horsepower (746 W) for a short period of time. If a 70-kg athlete were to bicycle to the summit of a 500-m high mountain while expending power at this rate, she would have used at least ____ J of energy
a. 746
b. 3.43 × 10^5
c. 3.73 × 10^5
d. 7.46 × 10^5
e. 2.61 × 10^7
B
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The most abundant component of Titan's atmosphere is
A) methane B) carbon dioxide C) nitrogen D) oxygen
In composition, asteroids and meteoroids are most like:
A) jovian planets. B) Kuiper Belt objects. C) comets. D) terrestrial planets. E) the moons of Jupiter.
A mass m = 73 kg slides on a friction-less track that has a drop, followed by a loop-the-loop with radius R = 18.1 m and finally a at straight section at the same height as the center of the loop (18.1 m off the ground). Since the mass would not make it around the loop if released from the height of the top of the loop (do you know why?) it must be released above the top of the loop-the-loop height. See the Figure 5. (Assume the mass never leaves the smooth track at any point on its path.)
1) What is the minimum speed the block must have at the top of the loop to make it around the loop-the-loop without leaving the track?
2) What height above the ground must the mass begin to make it around the loop-the-loop?
3) If the mass has just enough speed to make it around the loop without leaving the track, what will its speed be at the bottom of the loop?
4) If the mass has just enough speed to make it around the loop without leaving the track, what is its speed at the final at level (18.1 m off the ground)?
5) Now a spring with spring constant k = 15300 N/m is used on the final at surface to stop the mass. How far does the spring compress?
6) It turns out the engineers designing the loop-the-loop didn't really know physics { when they made the ride, the fi rst drop was only as high as the top of the loop-the-loop. To account for the mistake, they decided to give the mass an initial velocity right at the beginning. How fast do they need to push the mass at the beginning (now at a height equal to the top of the loop-the-loop) to get the mass around the loop-the-loop without falling off the track?
Gasoline can be used to power cars because it has
A) gravitational potential energy. B) chemical potential energy. C) electrical potential energy. D) kinetic energy. E) radiative energy.