SOLVED
1. A 3 kg plastic tank that has a volume of 0.4 m3 filled with liquid water. Assuming
the density of water is 1000 kg/m3. Determine the weight of the combined system.
mwater = 1000 * 0.4 = 400 kg
mtotal= 400 + 3 = 403 kg
Water
W = 403 * 9.81 (kg * m/s2)
= 3953.43 N
2. A 3kg rock is thrown upward with a force of 300 N at a location where the
gravitational acceleration is 9.79 m/s2 . Determine the acceleration of the rock in
m/s2. Ans: 90.21 m/s2.
3. A person gets into an elevator at the lobby level of a hotel with 50 kg suit case. He
gets out of the elevator at the 12th floor, i.e 43 m above. Determine the amount of
energy consumed by the motor of the elevator that in now stored in the suit case.
Ans: 21.0915kJ.
STUDENT EXERCISE:
1. Electric power is to be generated by installing a hydraulic turbine generator at a
sit 155m below the free surface of a large water reservoir that can supply water at
a rate of 3120 kg/s steadily. Determine the power generation potential.
2. Two sites are being considered for wind power generation. In the first site, the
wind blows steadily at 12 m/s for 1800 hrs per year, whereas in the second site the
wind blows at 18 m/s for 1500 hrs per year. Assuming the wind velocity is
negligible at other conditions. Determine which is the better site for wind power
generation.
1. A 3 kg plastic tank that has a volume of 0.4 m3 filled with liquid water. Assuming
the density of water is 1000 kg/m3. Determine the weight of the combined system.
mwater = 1000 * 0.4 = 400 kg
mtotal= 400 + 3 = 403 kg
Water
W = 403 * 9.81 (kg * m/s2)
= 3953.43 N
2. A 3kg rock is thrown upward with a force of 300 N at a location where the
gravitational acceleration is 9.79 m/s2 . Determine the acceleration of the rock in
m/s2. Ans: 90.21 m/s2.
3. A person gets into an elevator at the lobby level of a hotel with 50 kg suit case. He
gets out of the elevator at the 12th floor, i.e 43 m above. Determine the amount of
energy consumed by the motor of the elevator that in now stored in the suit case.
Ans: 21.0915kJ.
STUDENT EXERCISE:
1. Electric power is to be generated by installing a hydraulic turbine generator at a
sit 155m below the free surface of a large water reservoir that can supply water at
a rate of 3120 kg/s steadily. Determine the power generation potential.
2. Two sites are being considered for wind power generation. In the first site, the
wind blows steadily at 12 m/s for 1800 hrs per year, whereas in the second site the
wind blows at 18 m/s for 1500 hrs per year. Assuming the wind velocity is
negligible at other conditions. Determine which is the better site for wind power
generation.
