Question

An air rifle pellet of mass 2g is fired at an initial speed of 200 m/s into a stationary block of clay. It penetrates the block for a distance of 10 cm before coming to rest. What is the average force acting on the pellet from the block of clay?

Answer 1

The average force acting on a pellet from a block of clay, when the pellet comes to rest after penetrating the block for a distance, is calculated using the work-energy principle. The force is found to be 400 newtons.

Step-by-step explanation:

To calculate the average force acting on a pellet from a block of clay, we can use the work-energy principle. The work done by the force is equal to the change in kinetic energy of the pellet. When the pellet stops, its kinetic energy is zero, so the work done is equal to the initial kinetic energy of the pellet.

The initial kinetic energy (KE) is given by the formula KE = 0.5 × mass × speed^2. For a mass of 2g (0.002 kg) and a speed of 200 m/s, the initial KE is:

KE = 0.5 × 0.002 kg × (200 m/s)^2 = 40 J

The work done (W) by the average force (F) over the penetration distance (d) of 10 cm (0.10 m) is W = F × d, which is equal to the initial KE. Therefore, F = KE / d.

F = 40 J / 0.10 m = 400 N

So, the average force exerted on the pellet by the clay is 400 newtons (N).

Answer 2

C. 4x10^2 N

See the picture. We solved for the force of the pellet on the clay. But according to Newton’s third law, the clay acts with an equal and opposite force, which changes the direction from negative to positive.