scen discussion questions

what is the meaning of quantity in physics

anything about an object that you can measure and describe using a number and a specific unit

alex says acceleration is how fast you go. Natalie says acceleration if how fast you get. They look to you for confirmation. Who’s correct and why?

natalie is correct because alex is describing speed. natalie is stating the rate at which speed changes (how fast you get), which is acceleration

in tearing a paper towel roll or a plastic bag from a roll, why a sharp jerk is better than a slow pull?

When you jerk the towel quickly, the roll’s inertia resists moving, so only one piece tears off. When you pull the towel slowly, the roll can start turning easily, so the towel just unwinds instead of tearing.

why is a massive cleaver more effective for chopping vegetables than a lighter knife that is equally sharp? explain

the massive cleaver tends to keep moving when it encounters vegetables, cutting them more effectively.

a common saying goes, “it’s not that fall that hurts you, its the sudden stop” translate this into newtons 2nd law

the sudden stop involved a large acceleration

why will a girl wearing gym shoes win in a tug-of-war against a boy wearing socks while the activity occurs on a smooth floor? explain

the gym shoes give more friction compared to the socks on the smooth floor, meaning that the girl would be able to exert more pulling force without slipping

why is it a good idea to have your knees bent when you land after a jump?

bending your knees after landing a jump increases the time that your momentum changes which minimizes the impact force

what does it mean to say a quantity is conserved?

its value remains constant over time

Freddy frog drops vertically from a tree onto a horizontally moving skateboard. the skateboard slows. give a reason for the slowing in terms of momentum conservation

no external forces act in the horizontal direction, since freddy’s mass is added, velocity must decrease

a pair of skaters initially push at rest against each other, so they move in opposite directions. A). what is the total momentum as the skaters push apart? B). is there a different answer if their masses are not the same?

A). the momentum is zero

B). each will have the same amount of momentum, but different speeds.

A). can something have energy without having momentum?

B). can something have momentum without having energy

A). yes, an object can have potential energy

B). no, any moving object must have both momentum and kinetic energy

how does this bulge affect the relationship between a person’s weight in singapore, and his or her weight in delaware?

the bulge of a person in singapore is farther from the earth’s center and therefore weighs less

newton tells us that gravitational force acts on all bodies in proportion to their masses. why, then, does not a heavy body fall faster than a lighter body?

the acceleration due to gravity is constant and does not depend upon the mass of an object

why do the passengers in high-altitude jet planes feel the sensation of weight while passengers in the space station do not?

the plane moves at about constant velocity, so a passenger experiences normal weight