Solution
The energy the rocket has at "C" is all kinetic. The amount of kinetic energy is equal to the gravitational potential energy at "A".
v = 54.22m/s
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Solution
The rocket has only gravitational potential energy at "A". The
mass of the rocket does not include the mass of fuel which is exhausted
by the time the rocket reaches peak altitude.
mgh = 650 X 9.8 X 150 = 955500 joules.
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Solution
The rocket at "B" has a mass of 650kg and a speed of 34m/s. Its
kinetic energy can be calculated according to the expression below
0.5 X 650 X 34 X
34 = 375700joules
Now the rocket at
point "A" had a potential energy of mgh = 650 X 9.8 X 150 =955,500
joules. Since there is no energy loss the amount of gravitational potential
energy at "B" is given by the expression
955,500 - 375,700 =579,800joules
The expression below can be used to find the height.
579,800 =mgh=650 X 9.8 X h
=> 91.02m = h
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Solution
The energy the rocket has at "C" is all kinetic. The amount of kinetic energy is equal to the gravitational potential energy at "A".
v = 54.22m/s
Click to hide solution
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Gravitational
into kinetic exercises 3
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1) A rocket has a total mass of 1500kg (includes 850 kg of fuel) sits on the launch pad. After launch it reaches a maximum altitude of 150m where it momentarily comes to a stop. Assume no air resistance or energy loss from the system.
Solution b)
What is the height of the rocket at "B" if its speed is 34m/s?
Solution c) What is the speed of the rocket at "C" assuming that "C" is at ground level. Solution |
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