How to Calculate the Impact Force at Right Angles

The Falling Body Problem

• 1

  Determine the height (s) from which the dropped object will fall. Measure the object's mass (m). Select the correct acceleration due to gravity (g). Depending upon the other units, g will be either 9.8 m/s2 (metric) or 32 ft/s2.

  For example, consider a bowling ball with a mass of four kilograms. Hold the ball two meters above the ground and then drop it. The ball hits the ground and sinks 0.1 meters. Calculate the impact force.

• 2

  Calculate the potential energy (Ep) by multiplying s, m and g together.

  For the dropped bowling ball, this will be 2*4*9.8 = 78.4 Joules.

• 3

  Measure the distance (d) the object continued after impact before stopping. Calculate the impact force (Fi) by dividing the Ep by d.

  Continuing the bowling ball example, the impact force will be 78.4/0.1 = 784 Newtons.

The Moving Body Problem

• 4

  Determine the moving object's velocity at the moment of collision (v). Measure the mass (m) of the vehicle.

  For example, consider a speeding car with mass 1000 kilograms and a velocity of 20 meters/second. When the car strikes a concrete barrier, its front end crumples 2 meters before the car comes to rest.

• 5

  Calculate the kinetic energy at the point of impact (Ek) by squaring v, multiplying by m and dividing by 2.

  In the crashing car example, the kinetic energy is equal to (20*20*1000)/2 or 100,000 Joules.

• 6

  Measure the distance (d) the object continued moving after impact until it stopped. Calculate the impact force (Fi) by dividing Ek by d.

  Continuing the crashing car example, we calculate the impact force to be 100,000/2 = 50,000 Newtons.