Butanol Isomers

Butanol Isomers

Unit 1 Forces and Motion: Dynamics
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(Pages 2–3)

Knowledge and Understanding
Scalar quantities include distance (metre, 5.0 m), time (second, 15 s), mass (kilogram, 65 kg), and frequency (hertz, 60 Hz). Vector quantities include velocity (metres per second, 15 m/s [E]), displacement (metre, 6.5 m [S]), acceleration (metres per second squared, 9.8 m/s2 [down]), and force (newton, 25 N [forward]). 2. (a) Both masses will hit the floor at the same time since the speed at which an object falls is independent of mass, and is related only to acceleration due to gravity (neglecting air resistance). (b) 1.

(c) m = 20 g = 0.02 kg Fg = ? Fg = mg = (0.02 kg)(9.8 N/kg [down]) Fg = 0.2 N [down] The weight of the 20-g mass is 0.2 N [down]. (d) One example is the force of Earth pulling downward on the 20-g mass and the force of the 20-g mass pulling upward on Earth. GM E mMoon The magnitude of the force of gravity between Earth and the Moon depends linearly on the masses of 3. FG = r2 Earth and the Moon, and depends inversely as the square of the distance between the centres of Earth and the Moon. 4. (a) Kinematics is the study of motion (e.g., analyzing motion with constant acceleration). Dynamics is the study of the causes of motion (e.g., analyzing forces by applying Newton’s three laws of motion). (b) Average speed is a scalar quantity, v
av = total distance total time

. Average velocity is a vector quantity, vav =

change of position time interval

.

(c) Static friction is a force that acts to prevent a stationary object from starting to move. Kinetic friction is a force that acts against a moving object. For a given situation, kinetic friction tends to be less than maximum static friction. (d) Helpful friction is needed in many cases (e.g., turning a doorknob, walking, and travelling around a corner on a highway). Unwanted friction usually increases the production of waste heat (e.g., friction in the moving parts of an engine). (e)...