What is the kinetic energy of an object with a mass of 16 kg that has been in freefall for 2 s?
1 Answer
Explanation:
Recall that the formula for kinetic energy is:
color(blue)(|bar(ul(color(white)(a/a)DeltaE_k=1/2mDeltav^2color(white)(a/a)|))) where:
DeltaE_k= change in kinetic energy
m= mass
Deltav= change in velocity
Step 1
In order to use the kinetic energy formula, you first need to determine the initial velocity, which can be found by using the rearranging the formula for acceleration.
a=(Deltav)/(Deltat)
a=(v_f-v_i)/(Deltat)
aDeltat=v_f-v_i
v_i=v_f-aDeltat
Step 2
Substitute
DeltaE_k=1/2mDeltav^2
DeltaE_k=1/2m(v_f-v_i)^2
DeltaE_k=1/2m(v_f-color(darkorange)((v_f-aDeltat)))^2
DeltaE_k=1/2m(aDeltat)^2
Plug in the values.
DeltaE_k=1/2(16kg)((9.81m/s^2)(2s))^2
Solve.
DeltaE_k=1/2(16kg)(384.9444m^2/s^2)
DeltaE_k=3079.5552J
DeltaE_k=color(green)(|bar(ul(color(white)(a/a)color(black)(3000J)color(white)(a/a)|)))