A university campus has 200 classrooms and 400 faculty offices. The classrooms are equipped with 12 fluorescent tubes, each consuming $110 \mathrm{~W}$, including the electricity used by the ballasts. The faculty offices, on average, have half as many tubes. The campus is open $240$ days a year. The classrooms and faculty offices are not occupied an average of $4 \mathrm{~h}$ a day, but the lights are kept on. If the unit cost of electricity is $\$ 0.082 / \mathrm{kWh}$, Find how much the campus will save a year if the lights in the classrooms and faculty offices are turned off during unoccupied periods.

Determine the power required for a $1150$-$~\mathrm{kg}$ car to climb a $100$-$~\mathrm{m}$-long uphill road with a slope of $30^\circ$ (from horizontal) in $12 \mathrm{~s}$

(a) at a constant velocity,

(b) from rest to a final velocity of 30 m/s, and

(c) from 35 m/s to a final velocity of 5 m/s. Disregard friction, air drag, and rolling resistance.

A construction crane lifts a prestressed concrete beam weighing $2$ tons from the ground to the top of piers that are $18 \mathrm{~ft}$ above the ground. Find the amount of work done considering $(a)$ the beam and $(b)$ the crane as the system. Express your answers in both $\mathrm{lbf} \cdot \mathrm{ft}$ and $\mathrm{Btu}$.

Find the power required for a $2000-\mathrm{kg}$ car to climb a $100-\mathrm{m}$-long uphill road with a slope of $30^{\circ}$ (from horizontal) in $10 \mathrm{~s}(a)$ at a constant velocity, $(b)$ from rest toa final velocity of $30 \mathrm{~m} / \mathrm{s}$, and (c) from $35 \mathrm{~m} / \mathrm{s}$ to a final velocity of $5 \mathrm{~m} / \mathrm{s}$. Disregard friction, air drag, and rolling resistance.

A construction crane lifts a prestressed concrete beam weighing 3 short tons from the ground to the top of piers that are 24 ft above the ground. Determine the amount of work done considering

(a) the beam and (b) the crane as the system.

Express your answers in both lbf.ft and Btu.

The lighting needs of a storage room are being met by six fluorescent light fixtures, each fixture containing four lamps rated at 60 W each. All the lamps are on during operating hours of the facility, which are 6 a.m. to 6 p.m. 365 days a year. The storage room is actually used for an average 3 h a day. If the price of electricity is $0.11/kWh, determine the amount of energy and money that will be saved as a result of installing motion sensors. Also, determine the simple payback period if the purchase price of the sensor is$32 and it takes 1 h to install it at a cost of $40.

A construction crane lifts a prestressed concrete beam weighing 3 short tons from the ground to the top of piers that are 24 ft above the ground. Determine the amount of work done considering (a) the beam and (b) the crane as the system. Express your answers in both lbfft and Btu.

A small electrical motor produces 5 W of mechanical power. What is this power in (a) N, m, and s units; and (b) kg, m, and s units?

A pressure cooker cooks a lot faster than an ordinary pan by maintaining a higher pressure and temperature inside. The lid of a pressure cooker is well sealed, and steam can escape only through an opening in the middle of the lid. A separate metal piece, the petcock, sits on top of this opening and prevents steam from escaping until the pressure force overcomes the weight of the petcock. The periodic escape of the steam in this manner prevents any potentially dangerous pressure buildup and keeps the pressure inside at a constant value. Determine the mass of the petcock of a pressure cooker whose operation pressure is 120 kPa gage and has an opening cross-sectional area of $3 mm^2$. Assume an atmospheric pressure of 101 kPa, and draw the free-body diagram of the petcock.

A water pump increases the water pressure from 15 psia to 70 psia. Determine the power input required, in hp, to pump $0.8 ft^3/s$ of water. Does the water temperature at the inlet have any significant effect on the required flow power?

A vertical piston-cylinder device contains water and is being heated on top of a range. During the process, 65 Btu of heat is transferred to the water, and heat losses from the side walls amount to 8 Btu. The piston rises as a result of evaporation, and 5 Btu of work is done by the vapor. Determine the change in the energy of the water for this process. Answer: 52 Btu

As a spherical ammonia vapor bubble rises in liquid ammonia, its diameter changes from 1 cm to 3 cm. Calculate the amount of work produced by this bubble, in kJ, if the surface tension of ammonia is 0.02 N/m. Answer: 5.03 x 10^(-8) kJ

A damaged 1200-kg car is being towed by a truck. Neglecting the friction, air drag, and rolling resistance, determine the extra power required (a) for constant velocity on a level road, (b) for constant velocity of 50 km/h on a 30$^\circ{}$ (from horizontal) uphill road, and (c) to accelerate on a level road from stop to 90 km/h in 12 s. Answers: (a) 0, (b) 817 kW, (c) 31.3 kW

One kilogram of water vapor at 200 kPa fills the 1.1989-m^3 left chamber of a partitioned system . The right chamber has twice the volume of the left and is initially evacuated. Determine the pressure of the water after the partition has been removed and enough heat has been transferred so that the temperature of the water is 3$^\circ{}$C.