4.7 Work, energy, and power

• The angle θ in the work done formula represents the angle between the force and the direction of motion.

  True
• What is the most accurate formula for calculating work done?

  Fd cos θ
• What type of work is done when friction slows down an object?

  Negative
• 1 kWh is equivalent to 3,600,000 J.


  True
• Kinetic energy is measured in Joules (J).


  True
• One foot-pound is equal to 1.356 joules.


  True
• Match the variable with its unit:

  Kinetic Energy ↔️ Joules

  Mass ↔️ Kilograms

  Velocity ↔️ Meters per second
• A 5 kg ball moving at 8 m/s has a kinetic energy of 160 J.


  True
• Match the scenario with the type of work done:

  Lifting an object against gravity ↔️ Positive work

  Object slowing down due to friction ↔️ Negative work
• Work done can be positive or negative depending on the scenario.
• One kilowatt-hour is equal to 3,600,000 Joules.


  True
• What is the definition of work done?

  Energy transferred by force
• What is the sign of work done when lifting an object against gravity?

  Positive
• In the formula W = Fd cos θ, W represents work done and is measured in Joules
• If a force of 50 N pushes a block 5 meters parallel to the direction of motion, the work done is 250
• What is the definition of kinetic energy?

  Energy due to motion
• What is the standard SI unit for work done?

  Joules
• Kinetic energy is the energy an object possesses due to its motion.
• What happens to kinetic energy if velocity doubles?

  It quadruples
• What is work done defined as?

  Energy transferred by force
• As work done increases, the potential energy of the object may also increase.


  True
• What is the standard SI unit for work done?

  Joule (J)
• How many Joules are in one foot-pound?

  1.356 J
• How many foot-pounds are in 500 Joules?

  368.7 ft-lb
• Kinetic energy is directly proportional to the mass and the square of the velocity.
• Match the energy types with their definitions and formulas:

  Kinetic Energy ↔️ Energy of motion, $K =$$\frac{1}{2}mv^{2}$

  Potential Energy ↔️ Stored energy, $U =$$mgh$
• Electron volts are commonly used in mechanics to measure kinetic energy.

  False
• Gravitational potential energy is the energy an object possesses due to its position in a gravitational field.
• What is the gravitational potential energy of a 5 kg object lifted 2 meters above the ground?

  98 J
• What is the unit of gravitational potential energy?

  Joules
• Gravitational potential energy increases as height increases.

  True
• The gravitational potential energy of an object decreases as its height decreases.


  True
• What is the definition of work done in physics?

  Energy transferred by force
• In which scenario is work done positive?

  Lifting an object
• What is the standard SI unit for work done?

  Joule
• What is the formula for kinetic energy?

  K = \frac{1}{2}mv^{2}</latex>
• What is the kinetic energy of a 5 kg ball moving at 8 m/s?

  160 J
• In the kinetic energy formula, \(v\) represents the velocity
• The gravitational potential energy formula is $U =$$mgh$
• Kinetic energy increases linearly with velocity.

  False