I need to figure out how to calculate the speed time and acceleration for a jetpack to lift a 75kg man from ground. I am not sure what equations I need to use. I realize that gravity has to come in to play but other than that I am lost.

To calculate the speed, time, and acceleration required for the jetpack to lift a 75kg man from the ground, there are a few steps you need to follow.

1. Calculate the force required to counteract gravity:
- The force required to lift an object against gravity can be determined using Newton's second law of motion: F = m * g
- In this equation, F is the force, m is the mass of the object (75kg), and g is the acceleration due to gravity (approximately 9.8 m/s^2).

2. Determine the acceleration provided by the jetpack:
- The acceleration provided by the jetpack will counteract the force of gravity.
- You can use the equation F = m * a to solve for acceleration (a). Plug in the mass of the person (75kg) and the force calculated in step 1.

3. calculate the speed:
- Once you have the acceleration, you can calculate the speed using one of the kinematic equations of motion.
- The equation v = u + a * t can be used to calculate the final speed (v) where:
- u is the initial velocity, which we assume to be zero since the person is starting from rest.
- a is the acceleration, which we calculated in step 2.
- t is the time taken for the person to reach the desired speed.

4. Calculate the time taken:
- To find the time taken for the person to reach the desired speed, you need to know the distance over which the acceleration occurs.
- Without this information, it's challenging to calculate the exact time taken.
- However, if you assume the jetpack accelerates the person vertically, you can use the equation s = u * t + (1/2) * a * t^2, where:
- s is the distance traveled,
- u is the initial velocity (0 m/s),
- a is the acceleration calculated in step 2, and
- t is the time taken to reach the desired speed.

Keep in mind that these calculations are simplified, and in reality, there may be other factors, such as air resistance, that could affect the actual values.