An open knife edge of mass 200g is dropped from hieght 5m on a cardboard. If the knife edge penetrates 2m into the cardboard, the average resistance offered by the cardboard to the knife

To calculate the average resistance offered by the cardboard to the knife, we can use the principle of work and energy.

The work done by the average resistance force is equal to the change in kinetic energy of the knife edge. We can calculate the initial kinetic energy of the knife edge using the mass and initial velocity of the knife edge just before hitting the cardboard.

Since the knife edge is dropped from a height of 5m, the potential energy of the knife edge just before hitting the cardboard is given by:

Potential energy (PE) = mass * gravitational acceleration * height
= 0.2kg * 9.8m/s² * 5m
= 9.8 Joules

When the knife edge penetrates the cardboard, it comes to a stop. This means that all of its initial kinetic energy is spent in overcoming the resistance force of the cardboard.

The work done by the resistance force is equal to the force applied multiplied by the distance penetrated by the knife edge. We can rearrange the equation to solve for the average resistance force:

Work done (W) = Resistance force * Distance penetrated

Now, we know the distance penetrated is 2m. We can substitute the value of the work done (which is equal to the initial kinetic energy) and the distance penetrated into the equation to solve for the average resistance force:

Work done = Initial kinetic energy
Resistance force * Distance penetrated = 9.8 Joules
Resistance force * 2m = 9.8 Joules
Resistance force = 9.8 Joules / 2m
Resistance force = 4.9 Newtons

Therefore, the average resistance offered by the cardboard to the knife edge is 4.9 Newtons.

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Force*distance= work

force*2=.2*g*5 (the potentialenergy of the knife at 5 meters)

force= 50*g Newtons
this is pretty lame cardboard.