# Calculating the Force on impact?

• Tadhg
In summary, the motorcycle collides with an object at a distance of 1.3 m and the impact force is 2924.97 N.
Tadhg
Hi folks, this is a problem I am having in a collage project I am doing. I'm not too sure about my results and keep chasing my tail using the same formulas, e.g. F=ma etc. I think I need to allow for the fact that the force is applied as a collision but I am not sure how or if I need to do it.
So the big question, is the force that is applied to the ground to accelerate the bike the same as the force that is applied to the object that it impacts? I have tried to provide all the relevant data, but please ask if you need more.
Thank you.

1. Homework Statement

A motorcycles engine provides a torque of 46.91 Nm the transmission multiples this torque to 1053.87 Nm. This torque applied to the ground through a wheel with an outer diameter of 0.72 m. The motorcycles front wheel hits an object at a distance of 1.3 m. Bike and rider mass=194.37 kg.Force = torque/distance
Force = 1053.87/(0.72/2)
Force applied to the ground to accelerate the motorcycle = 2924.97 N

Force=mass x acceleration
F=ma
a = 2924.97/194.37
a=15.05 m/s^2

Final Velocity^2 = Initial Velocity^2 + 2 x acceleration x distance
V^2=U^2+2as
V = squrt(0+2x15.05x1.3)
velocity = 6.14 m/s

Kinetic Energy = 1/2 x mass x velocity^2
Ek = 0.5 x 194.37 x 6.14^2
Kinetic Energy = 3664.67 Joules

Assuming no losses and that there is an instantaneous transfer of torque to the ground etc.

Tadhg said:

The motorcycles front wheel hits an object at a distance of 1.3 m.

It isn't clear what you mean by that statement.

Stephen Tashi said:
It isn't clear what you mean by that statement.

Sorry,The motorcycle is at rest with the front wheel of the motorcycle at a distance of 1.3 m from the object. The motorcycle then accelerates from rest and collides with the object.

So the big question, is the force that is applied to the ground to accelerate the bike the same as the force that is applied to the object that it impacts?

No. Force isn't conserved.
Momentum is conserved and sometimes energy is conserved depending on the nature of the impact.

There are several ways to work out what the impact force might be but you need to know more about the nature of the collision. For example if the bike ran into something that caused it to stop in say 0.5 meters you could work out the average force that the object applied to the bike.

Edit: but would the rider also stop in 0.5 meters :-)

PS: Note that short stopping distances equate to high forces and a zero length stopping distance would imply infinite force. Something has to give.

Ok so, if the motorcycle collides with the object and the object is a cantilever, if the collision is with the free end of the cantilever the free end deflection could be considered the distance it takes to stop. Then work out the average force applied to the bike?

PS: I know first hand that the rider only stops if he meets the object in question! But its ok because there is plenty of friction between ride/road to slow you down!

Thank you for the advice I think I have it now

## 1. How do you calculate the force on impact?

The force on impact can be calculated using the formula F = m x a, where F is the force, m is the mass of the object, and a is the acceleration. This formula applies to both stationary and moving objects.

## 2. What is the difference between force on impact and force of impact?

The force on impact refers to the force experienced by an object upon hitting a surface, while the force of impact refers to the force exerted by an object on another object upon collision. Both terms are often used interchangeably, but they have different meanings.

## 3. How does the speed of an object affect the force on impact?

The force on impact increases as the speed of an object increases. This is because a higher speed means a higher rate of change in momentum, which results in a greater force upon impact.

## 4. Can the angle of impact affect the force?

Yes, the angle of impact can affect the force on impact. When an object hits a surface at an angle, the force is distributed over a larger area, resulting in a lower force on impact compared to a direct hit at the same speed.

## 5. How do you calculate the force on impact for a falling object?

To calculate the force on impact for a falling object, you can use the formula F = 1/2 x m x v^2, where F is the force, m is the mass of the object, and v is the velocity or speed at impact. This formula takes into account the gravitational force acting on the object during its fall.

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