Question

The 2-kg blade of an ax is moving at 60 m/s when it strikes a log. If the blade penetrates 2 cm into the log as its kinetic energy is turned into work, the average force it exerts is:

a) 3 kN
b) 90 kN
c) 72 kN
d) 180 kN

Answer 1

The average force exerted by the blade of an ax is 180 kN.

Step-by-step explanation:

To find the average force exerted by the blade of an ax when it penetrates a log, we need to use the work-energy principle. We know that the initial kinetic energy of the blade is equal to the work done on the log. The initial kinetic energy of the blade can be calculated using the equation:

K.E. = (1/2)mv^2

where m is the mass of the blade (2 kg) and v is its velocity (60 m/s). By substituting the values, we get:

K.E. = (1/2)(2 kg)(60 m/s)^2 = 3600 J

The work done on the log is given by the equation:

Work = Force × Distance

Here, the distance is given as 2 cm which is equal to 0.02 m. By rearranging the equation, we can find the force:

Force = Work / Distance

Force = 3600 J / 0.02 m = 180,000 N

Therefore, the average force exerted by the blade is 180 kN (option d).