Recent content by lordbolton

nevermind, i got it.

A 30kg sledge hammer strikes a steel spike of 2.30 cm diameter while moving at 20.9 cm/s. The hammer rebounds with a speed of 10.0 cm/s after 0.110 s. What is the average strain in the spike during impact? 2. F = (mvf-mvi)/t S = (F/A)/(deltaL/initialL) Young's modulus for steel = 2 x...

Tried it again, got x = 10.02m. So thanks for the help. Are my a) and b) correct though?

Also tried using the equation mgy + (1/2)(k)(39.2-y)^2 = 40,768 and solving using the quadratic formula which gave y as 7.47

mgy at 39.2 is 25,213 J. So I subtract that from the total energy 40,768J which leaves 15,554.56J Then I equate that with (.5)(81)(y^2) and solve for y which gives 19.61

So I used your correction and recalculated and got y = 19.597 which seems correct. Is that the right answer though? I have no way to check.

1. Starting from rest, a 64kg person bungee jumps from a tethered balloon 65m high. The cord has unstretched length 25.8m. The cord is modeled as a spring that obeys hooke's law with spring constant 81N/m and the person's body is modeled as a particle. The balloon does not move. a) Express the...