Two students push a 20.0\,\text{kg}20.0kg20, point, 0, start text, k, g, end text desk from opposing directions. One student pushes with a force of 5.0\,\text{N}5.0N5, point, 0, start text, N, end text to the left, and the other student pushes with a force of 2.0\,\text{N}2.0N2, point, 0, start text, N, end text to the right. Calculate the horizontal acceleration of the desk.

Amass has an acceleration of 10- 2t. what is its velocity and displacement if it started at x- 4m and the initial velocity was 8m/s? at what time does it have 0 velocity? graph all graphs.

Which lists the main components of darwin’s theory of evolution? a. random mutations drive evolution; the evolution of a population happens slowly; organisms have common ancestors; organisms do not change. b. natural selection drives evolution; the evolution of a population happens slowly; organisms have common ancestors; organisms change over time. c. natural selection drives evolution; the evolution of a population happens rapidly; organisms have common ancestors; organisms change over time. d. random mutations drive evolution; the evolution of a population happens rapidly; organisms have common ancestors; organisms do not change.

The atoms in a nickel crystal vibrate as harmonic oscillators with an angular frequency of 2.3 × 1013 rad/s. the mass of a nickel atom is 9.75 × 10-26 kg. what is the difference in energy between adjacent vibrational energy levels of nickel? (h = 6.626 × 10-34 j • s, , 1 ev = 1.60 × 10-19 j)