Ch 20: The First Law of ThermodynamicsWorksheetSee all chapters
All Chapters
Ch 01: Units & Vectors
Ch 02: 1D Motion (Kinematics)
Ch 03: 2D Motion (Projectile Motion)
Ch 04: Intro to Forces (Dynamics)
Ch 05: Friction, Inclines, Systems
Ch 06: Centripetal Forces & Gravitation
Ch 07: Work & Energy
Ch 08: Conservation of Energy
Ch 09: Momentum & Impulse
Ch 10: Rotational Kinematics
Ch 11: Rotational Inertia & Energy
Ch 12: Torque & Rotational Dynamics
Ch 13: Rotational Equilibrium
Ch 14: Angular Momentum
Ch 15: Periodic Motion (NEW)
Ch 15: Periodic Motion (Oscillations)
Ch 16: Waves & Sound
Ch 17: Fluid Mechanics
Ch 18: Heat and Temperature
Ch 19: Kinetic Theory of Ideal Gasses
Ch 20: The First Law of Thermodynamics
Ch 21: The Second Law of Thermodynamics
Ch 22: Electric Force & Field; Gauss' Law
Ch 23: Electric Potential
Ch 24: The Wave Nature of Light
Ch 24: Capacitors & Dielectrics
Ch 25: Resistors & DC Circuits
Ch 26: Magnetic Fields and Forces
Ch 27: Sources of Magnetic Field
Ch 28: Induction and Inductance
Ch 29: Alternating Current
Ch 30: Electromagnetic Waves
Ch 31: Geometric Optics
Ch 32: Wave Optics
Ch 34: Special Relativity
Ch 35: Particle-Wave Duality
Ch 36: Atomic Structure
Ch 37: Nuclear Physics
Ch 38: Quantum Mechanics

Concept #1: Changes in Internal Energy

Concept #2: The First Law of Thermodynamics

Practice: 2.5 moles of an atomic hydrogen gas are stored in a cylinder with a moveable piston, sitting in a bucket of ice. The piston is moved SLOWLY, decreasing the volume from 0.03 m3 to 0.01 m3 . How much ice melts during this movement? Work done at constant pressure is given by 𝑊 = −𝑃Δ𝑉, and work done at constant temperature by 𝑊 = −𝑛𝑅𝑇𝑙𝑛 ( 𝑉𝑓/𝑉𝑖 ). Note that the latent heat of fusion for water is 334 kJ/kg.

Additional Problems
An athlete doing push-ups performs 650 kJ of work and loses 425 kJ of heat. What is the change in the internal energy of the athlete? a) -225 KJ b) -1075 KJ c) 1075 KJ d) 225 KJ  
A skater pushes straight away from a wall. She pushes on the wall with a force whose magnitude is F, so the wall pushes on her with a force F (in the direction of her motion). As she moves away from the wall, her center of mass moves a distance d. Consider the following statements regarding energy. I ΔKtrans + ΔEinternal = Fd II. ΔKtrans + ΔEinternal = −Fd III. ΔKtrans + ΔEinternal = 0 IV. ΔKtrans = Fd V. ΔKtrans = −Fd What is the correct form of the energy principle for the skater as a real system and as a point particle (PP) system? 1. Real: II, PP: V 2. Real: I, PP: V 3. Real: II, PP: IV 4. Real: V, PP: I 5. Real: IV, PP: III 6. Real: III, PP: IV 7. Real: V, PP: IV 8. Real: I, PP: IV 9. Real: III, PP: V 10. Real: IV, PP: IV
Consider the head-on collision of two masses, m1 = 3 kg moving to the right with speed 6 m/s and m2 = 6 kg moving to the left with speed 3 m/s. Given that they stick together after the collision, what is the increase in internal energy of the system during the collision? Assume no energy is lost to the surroundings and neglect any external forces acting on the two masses. 1. 81.0 J 2. 56.25 J 3. 40.5 J 4. 216.0 J 5. 303.75 J 6. 112.5 J 7. 144.0 J 8. 375.0 J 9. 525.0 J 10. 72.0 J
Six moles of a monatomic ideal gas undergo the process shown in the figure. State 1 has pressure p1 = 4.00 x 105 Pa and volume V1 = 2.00 x 10-3 m3. State 2 has pressure p2 = 3.00 x 105 Pa and volume V2 = 6.00 x 10-3 m3.  a) In this process, what is ΔU, the change in the internal energy of the gas? b) What is the heat flow Q for this process?  c) Does heat flow into the gas or out of the gas?      
The temperature of 5.0 moles of an ideal gas is increased from 100°C to 300°C. If this is done at constant volume, 3.0 x 104 J of heat energy flows into the gas. If the same temperature change is carried out at constant pressure, the heat flow into the gas is (a) 3.0 x 104 J (b) less than 3.0 x 104 J (c) greater than 3.0 x 104 J