Final answer:
Lisa must exert a minimum force of 588 N to lift a 60 kg barbell off her chest, which is equal to the weight of the barbell.
Step-by-step explanation:
Lisa needs to exert a force that is at least equal to the weight of the 60 kg barbell to lift it off her chest. The weight of the barbell can be calculated by multiplying its mass by the acceleration due to gravity (g = 9.8 m/s2). Therefore, the weight W = m × g = 60 kg × 9.8 m/s2 = 588 N. So, Lisa needs to produce a minimum force of 588 N to just lift the barbell upward and overcome the force of gravity acting on it.