Ch 07: Work & EnergyWorksheetSee 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: 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

Example #1: More Work-Energy #1

Example #2: More Work-Energy #1

Practice: A 3-kg box is sliding on a smooth level surface with 8 m/s when it enters a 5 m rough patch. If the box has half its original speed at the end of the patch, calculate the coefficient of kinetic friction between the box and the surface.

Example #3: More Work-Energy #2

Practice: Interstate roads in the U.S. typically have a speed limit of 70 mph (31.3 m/s). How much work is needed to stop a 1,400 kg car moving at this speed?  How much force is needed to accomplish this in 2 m?

Practice: To prevent a crash, a driver slams on the brakes, causing his car to skid a total distance of 80 m before stopping. The road-car coefficients of friction are 0.6 and 0.8. Calculate the car’s initial speed (the car’s mass is unknown).

Example #4: More Work-Energy #3

Practice: A 500-kg load is originally at rest on the floor. A crane pulls the load vertically up on the box with a constant 7,500 N until it reaches a height of 20 m. Calculate the speed of the load once it reaches 20 m.

Practice: A 2-kg block is originally at rest at the bottom of a smooth inclined plane that makes 37° with the horizontal. You push the block with a constant 20 N directed up the plane. Find the block’s speed after you push it 5 m up the plane.