Final answer:
a) When the barbell is on the ground, it has no potential energy. b) After being lifted 2.3 m, the barbell has 2001.6 J of potential energy. c) The barbell has gravitational potential energy after being lifted.
Step-by-step explanation:
a) When the barbell is on the ground, it has no potential energy. Potential energy is the energy an object possesses due to its height above the ground. Since the barbell is on the ground, its height is zero, and therefore its potential energy is zero.
b) After being lifted 2.3 m, the barbell has potential energy due to its height. The potential energy can be calculated using the formula PE = mgh, where m is the mass, g is the acceleration due to gravity, and h is the height. In this case, the mass is 90 kg, the acceleration due to gravity is 9.8 m/s^2, and the height is 2.3 m. Plugging these values into the formula, we get PE = (90 kg)(9.8 m/s^2)(2.3 m) = 2001.6 J. Therefore, the barbell has 2001.6 J of potential energy after being lifted 2.3 m.
c) The barbell has gravitational potential energy after being lifted. Gravitational potential energy is the energy an object possesses due to its position in a gravitational field. In this case, the barbell has potential energy due to its height above the ground.
d) The work done to lift the barbell can be calculated using the formula W = Fd, where W is the work done, F is the force applied, and d is the displacement. In this case, the force applied is equal to the weight of the barbell, which is mg, where m is the mass and g is the acceleration due to gravity. Plugging in the values, we get W = (90 kg)(9.8 m/s^2)(2.3 m) = 1991.4 J. Therefore, Austin did 1991.4 J of work to lift the barbell.
e) Power is the rate at which work is done, and it can be calculated using the formula P = W/t, where P is power, W is work, and t is time. In this case, the work done is 1991.4 J and the time taken is 1.9 s. Plugging in the values, we get P = 1991.4 J / 1.9 s = 1047.57 W. Therefore, Austin's power is 1047.57 W.