A 3 kg object is moving with a velocity of 4 m/s. If it comes to a stop, what is

Practice Questions

Q1
A 3 kg object is moving with a velocity of 4 m/s. If it comes to a stop, what is the work done by the friction force?
  1. -24 J
  2. -48 J
  3. -12 J
  4. -36 J

Questions & Step-by-Step Solutions

A 3 kg object is moving with a velocity of 4 m/s. If it comes to a stop, what is the work done by the friction force?
  • Step 1: Identify the mass of the object, which is 3 kg.
  • Step 2: Identify the initial velocity of the object, which is 4 m/s.
  • Step 3: Calculate the kinetic energy of the object using the formula: Kinetic Energy = 0.5 × mass × (velocity)².
  • Step 4: Plug in the values: Kinetic Energy = 0.5 × 3 kg × (4 m/s)².
  • Step 5: Calculate (4 m/s)², which is 16 m²/s².
  • Step 6: Multiply 0.5 × 3 kg × 16 m²/s² to get 24 J.
  • Step 7: Since the object comes to a stop, the work done by the friction force is equal to the negative of the kinetic energy.
  • Step 8: Therefore, Work done by friction = -24 J.
  • Work-Energy Principle – The work done by the friction force is equal to the change in kinetic energy of the object.
  • Kinetic Energy Calculation – Kinetic energy is calculated using the formula KE = 0.5 × mass × velocity².
  • Sign of Work Done – Work done by friction is negative because it acts in the opposite direction to the motion.
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