2.20 kg snowball is fired from a cliff 13.9 m high. The snowball\'s initial velo
ID: 1362433 • Letter: 2
Question
2.20 kg snowball is fired from a cliff 13.9 m high. The snowball's initial velocity is 10.7 m/s, directed 40.0 degree above the horizontal, (a) How much work is done on the snowball by the gravitational force during its flight to the flat ground below the cliff? (b) What is the change in the gravitational potential energy of the snowball-Earth system during the flight? (c) If that gravitational potential energy is taken to be zero at the height of the cliff, what is its value when the snowball reaches the ground?Explanation / Answer
a)
Sum of energy at the top=sum of energy at the ground
0.5mV^2+mgh=0.5mv^2+mgh
mass cancels out so:
0.5V^2+gh= 0.5v^2+gh
since height at the ground is zero:
0.5V^2+gh= 0.5v^2
now:
(0.5)(10.7^2)+(9.8)(13.9)=0.5v^2
solve for v to get 19.67 m/s
b)
Same speed, by conservation of energy.
c)
Same speed, by conservation of energy, mass does not matter.
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