Final answer:
The net force acting on a person with a mass of 70 kg during a handstand pushup, who applies an upward force of 760 N, is 74 N upward.
Step-by-step explanation:
To determine the net force acting on a person during a handstand pushup, we can use Newton's second law of motion, ΣF=ma, where ΣF is the net force, m is the mass, and a is the acceleration. Given that a person weighs 70 kg and applies a force of 760 N upward, we also need to consider the weight of the person (w), which is the force due to gravity: w=mg, where g is the acceleration due to gravity (9.80 m/s²).
The net force can be determined by using the equation F = ma + w, where F is the net force, m is the mass of the person, a is the upward acceleration, and w is the weight of the person. In this case, the mass of the person is 70 kg and the upward acceleration is 4 times the acceleration due to gravity, so a = 4 * 9.8 m/s^2. Plugging in these values, we get F = (70 kg)(4 * 9.8 m/s^2) + (70 kg)(9.8 m/s^2)
Thus, we have:
Net force (ΣF) = Applied force (F) - Weight (mg)
ΣF = 760 N - (70 kg × 9.80 m/s²)
ΣF = 760 N - 686 N
ΣF = 74 N
The ΣF is positive, indicating that the net force is upward, assisting the person in rising during the handstand pushup.