Work-Energy Solution

Question 1: Calculate the gravitational potential energy of a 2000-kg boulder raised 7 m above ground level.
State your assumption about g.

Solution: Assume g = 10 m/s²; PE = mgh = 2000 × 10 × 7 = 140,000 J.

Question 2: Calculate the kinetic energy of a 2-kg book tossed across the room at a speed of 4 m/s.
Solution: KE = ½mv² = 0.5 × 2 × 16 = 16 J.

Question 3: Calculate the kinetic energy of a 1000-kg car moving at 20 m/s.
Solution: KE = ½mv² = 0.5 × 1000 × 400 = 20,000 J.

Question 4: Calculate the work done when a 2-kg block of ice is moved from rest to a speed of 5 m /s.
Solution: work = ΔKE = 0.5 × 2 × 25 = 25 J.

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Date of last modification: Summer , 2019