Hannah made a chart to describe speed and velocity.
which best describes how to correct hannah's error?
speed
scalar quantity
calculated by dividing
time by distance
has magnitude
depends on a reference
frame
velocity
vector quantity
calculated by dividing
change in position by time
is a displacement
depends on a reference
frame
switch the chart headings "speed" and "velocity."
describe the calculation for speed as "dividing distance
by time."
in the "speed" column, change "has magnitude" to "is a
displacement."
change the last row of the "velocity" column to "does
not depend on a reference frame."

Ammonia enters the expansion valve of a refrigeration system at a pressure of 10 bar and a temperature of 18oc and exits at 6.0 bar. the refrigerant undergoes a throttling process. determine the temperature, in oc, and the quality of the refrigerant at the exit of the expansion valve.

An ideal otto cycle has a compression ratio of 10.5, takes in air at 90 kpa and 40°c, and is repeated 2500 times per minute. using constant specific heats at room temperature, determine the thermal efficiency of this cycle and the rate of heat input if the cycle is to produce 90 kw of power.

Aparticle's position is given by x = 3.00 - 9.00t + 3t2, in which x is in meters and t is in seconds. (a) what is its velocity at t = 1 s? (b) is it moving in the positive or negative direction of x just then? (c) what is its speed just then? (d) is the speed increasing or decreasing just then? (try answering the next two questions without further calculation.) (e) is there ever an instant when the velocity is zero? if so, give the time t; if not, answer "0". (f) is there a time after t = 3 s when the particle is moving in the negative direction of x? if so, give the time t; if not, answer "0".