An impact force is said to be existing whenever there is a change in momentum. Impact forces are capable of deforming the original shape of the object and cause damage. It is required to minimize the impact forces as much as possible in order to reduce the chances of damage and injuries. Newton’s second law of motion states that the magnitude of the force is equal to the product of mass and acceleration. Using this, the magnitude of impact force can be easily calculated, which is equal to the change in momentum divided by the total time taken for the change. Hence, to reduce the effect of impact force, the mass or the velocity can be reduced. However, it is not possible in certain cases, for example, the human mass, which cannot be forcefully reduced. Therefore, the best method of reducing the effect of impact force is to increase the time taken for the momentum to change.
Examples
1. Car Crash
An impact force exists whenever an object hits another object. A car moving with a certain velocity when encounters an obstacle, undergoes a change in momentum. This change in momentum is directly proportional to the existing impact force on the object in motion, which means that the greater be the change in momentum, the greater will be the impact force. The impact force is responsible for the damage and deformation caused to the car and the person driving it.
2. Parkour Running
Usually, when a parkour runner lands on the ground, he rolls his body over the ground. This is an act of minimizing the effect of impact force and the injuries caused by it. By landing and rolling over on the surface, the runner tends to increase the time with which his momentum changes. This time is inversely proportional to the magnitude of impact force. Therefore, his chances of being hurt are reduced.
3. Bungee Jumping
The rope used by the bungee jumper is highly elastic in nature. The rope stretches when the jumper jumps off the spot. The elasticity of the rope helps in increasing the time with which the momentum changes. This reduces the effect of impact force on the jumper and reduces the chances of an accident.
4. Smashing Egg
When an egg is thrown over a floor, it breaks as soon as it comes in contact with the rigid surface. This happens because the egg thrown with a particular velocity develops a momentum, which gets disrupted when it encounters a barrier. The sudden change in momentum generates enough impact force that is capable of breaking it into pieces.
5. Falling Objects
The objects falling freely due to the force of gravitation tend to develop momentum. This momentum remains constant if a constant velocity is maintained. If the object hits an obstacle or undergoes a change in velocity by any means, it is prone to develop a change in momentum. This change in momentum leads to the development of an impact force. This impact force has a different effect on different objects. The brittle object tends to break, while the object with a greater tensile strength might get deformed.
6. Cycling
Bicycles and motorbikes exert a considerable amount of impact force while landing vertically from a certain height. This can hurt the rider and can also cause damage to the bike. However, it can be easily avoided by employing suspension in bikes. Off-roading bikes are designed in a manner that they are able to increase the time over which the change in momentum takes place. The suspension system of the vehicle allows the vertical momentum to change over greater time than the vehicles that do not have any suspension system, and it decreases the effect of impact force, thereby allowing a safe landing to the rider.
7. Catching a Ball
Another example of an impact force in action can be seen when a cricketer catches a ball. When the ball reaches the player’s hands, he pulls his hands in the downward direction. By doing this, the player stretches the time with which the momentum of the ball changes, thereby reducing the magnitude of the impact force. If the player does not follow this method of stretching the time taken for momentum to change, he is more likely to get hurt.
8. Pole Vaulter
A pole vaulter develops a significantly high amount of momentum while taking a jump. When the jumper lands on the ground, the momentum possessed will quickly turn to zero. The large deceleration leads to intense injuries. To avoid this, the crash mat is designed in such a way that it ensures the time taken by momentum to change is significantly large. This results in the development of a smaller impact force. Hence, saving the athlete from injuries.
9. Safety Helmets
The safety helmets are properly cushioned from the inner side with the help of multiple foam layers. It provides safety to the person wearing it in case his/her head strikes a barrier. During a collision, the cushioned inner side of the helmet gets compressed and allows the momentum to change slowly. This increase in the time required to change the momentum decreases the impact force and saves the rider from fatal injuries.
10. Long Jump
A long jumper tends to land into a pit of sand and not on some hard floor. This is because the sand makes sure that the deceleration is as minimum as possible. The smaller be the deceleration value, the lesser will be the chances of injury. The momentum changes to zero after a long time. Hence, the impact force does not cause damage to the athlete’s body.