Which of the following examples does not illustrate Newton's first law of motion?
A. a glass of water sits motionless on a counter
B. a rocket engine accelerates a spacecraft along its trajectory
C. two students push on opposite sides of a desk, but it does not move
D. a hockey puck slides across smooth ice in a straight line at constant speed
PLEASE HELP

Which of the following changes will result in a stronger electromagnet? a. using fewer coils of wire b. using a higher voltage c. using a shorter nail d. using a longer wire

What is the measurement of how fast an object moves relative to a reference point?

Consider a one meter long horizontal pipe with a constant 100 cm^2 cross sectional area. water flows rightward into the pipe at x = 0 with flow velocity 02m/sec at every point within the pipe intake area. at x=1, the rightward flow rate is 0.192 m/sec. assume the water is a conserved quantity in the pipe, so there must be a leak (a sink) somewhere in the pipe. 1. compute net volumetric flow of the source if the system to be in equilibrium. 2. now assume the pipe in the problem has no leaks. compute the net volumetric rate of change for the system.