Answer:
a ) 2.68 m / s
b ) 1.47 m
Explanation:
The jumper will go down with acceleration as long as net force on it becomes zero . Net force of (mg - kx ) will act on it where kx is the restoring force acting in upward direction.
At the time of equilibrium
mg - kx = 0
x = mg / k
= (60 x 9.8 ) / 800
= 0.735 m
At this moment , let its velocity be equal to V
Applying conservation of energy
kinetic energy of jumper + elastic energy of cord = loss of potential energy of the jumper
1/2 m V² + 1/2 k x² = mg x
.5 x 60 x V² + .5 x 800 x .735 x .735 = 60 x 9.8 x .735
30 V² + 216.09 = 432.18
V = 2.68 m / s
b ) At lowest point , kinetic energy is zero and loss of potential energy will be equal to stored elastic energy.
1/2 k x² = mgx
x = 2 m g / k
= (2 x 60 x 9.8) / 800
= 1.47 m
The answer is B. helium-filled balloon, since sound travels the slowest through gases.
Answer:
C. a dense region of positive charge existed somewhere in the atom.
Explanation:
Physicist Ernest Rutherford created the gold foil experiment in which he shot a beam of alpha particles at a sheet of gold foil, which then sent a few of the particles flying after they were deflected. Based on the information gathered after completing this experiment, Rutherford concluded that a dense region of positive charge existed somewhere in the atom.
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Answer:
His average speed is 0.15 kilometer per minute or 2.5 meters per second.
Explanation:
average speed = distance/time
x = 3 km/20 minutes
x = 0.15
—
x = 3000 m/1200 s
x = 2.5
