The answer is 1. 4 is incorrect because you can't really decrease the mass of the driver. 3 is incorrect because accelerating the driver would cause more damage than not. 2 is incorrect because decreasing the distance would only cause more damage. 1 is correct because by increasing the length of time the force acts on the driver helps reduce the speed of the driver and cause the drive to sustain less injuries. Hope that helps.
Answer:
m/s
Explanation:
Assumption: bullet leaves the muzzle at a speed of V m/s
and velocity of push received by the man be v m/s
According to newton's third law to every action there is always an equal and opposite reaction.
therefore,
mass of man× velocity = mass of bullet×its velocity
⇒70×v= 10×10^-3 ×V
solving the above eqaution we get
therefore
m/s
Acceleration because it is at a rise in speed. The formula for acceleration is Speed/Time.
Thrust is a reaction force described quantitatively by Newton's third law. When a system expels or accelerates mass in one direction, the accelerated mass will cause a force of equal magnitude but opposite direction on that system. Mathematically can be written as,

Here,
v = speed of the exhaust gases measured relative to the rocket.
= Rate of change of mass with respect to time
Our values are given as,


Replacing we have that


Wavelength = 1/frequency thus wavelength =1/30000