Question

# 1) If a person holds 50 kg object at a height of 2 m above the...

1) If a person holds 50 kg object at a height of 2 m above the floor for 10 s. How much work is done? W = F×d

(2) The work done in lifting 30kg of bricks to a height of 20m is W = m ×g × d (Formula, W = F × d but Force = m × g)

(3) A total of 4900 J is used to lift a 50-kg mass. The mass is raised to a height (distance) of W = F ×d Formula W = m × g × d Formula

(4) A total of 490 J of work is needed to lift a body of unknown mass through a height of 10m. What is its mass? W = m × g × h Formula

(5) A 40-kg boy runs up a flight of stairs 4 m high in 4s. His power output is P = W/t Formula, Power = work/time, work = Force × distance P = m×g×h t

(6) A 1-kg object has kinetic energy of 1 J when its speed (velocity) is KE = 1/2 × m × v2

(7) A 1-kg object has potential energy of 1 J relative to the ground when it is at a height of PE = m × g × h (g = 9.8 m/s2)

(8) A weightlifter raises a 70-kg barbell from the floor to a height of 2.2 m in 1.2 s. What was his average power output during the lift? P = (W)/(t) Formula, Power = work/time, work = Force × distance Force = mass × gravity P = (m × g × h) /(t) (use this) (g = 9.8 m/s2)

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