chapter 9- forces Flashcards
difference between contact and non contact forces
contact forces need to be in physical contact during an interaction while non contact forces exert forces on another object from a distance
explain why the mass of an object does not change with its location while weight does
mass is the amount of matter in an object and it is not affected by gravitational force. the weight of an object on earth is due to the gravitational force exerted on the object by earth so the location changes the amount of gravitational force exerted on the object.
explain why atmospheric pressure decreases as we move up a mountain
the number of air particles pushing down on us decreases as we move up a mountain
state how the pressure underwater acting on us changes as we dive into the sea
the deeper we dive into the sea, the higher the water pressure acting on our body
explanation: because the number of air particles pushing down on us increases
how is it possible to drink water through a straw
(1) the action of sucking at the straw removes air from the straw
(2) the air pressure in the straw becomes lower than the atmospheric pressure outside the straw
(3) the atmospheric pressure presses on the water surface and pushes the water up the straw into the mouth
what are the conditions that must be satisfied for work to be done on an object
force is applied another object and it must move in the direction of force applied
on earth, 1kg=10N. what does that mean?
a mass of 1kg on earth has a weight of 10N
define the principle of conservation of energy
energy cannot be created or destroyed. it can only be converted from 1 form to another, and the total energy remains constant
1st difference between mass and weight
mass is measured by a beam balance while weight is measured by a spring balance
2nd difference between mass and weight
the SI unit of mass is Kilograms while for weight it is Newton
3rd difference between mass and weight
mass remains constant while weight changes with location
formula for pressure
pressure= force/area
formula for work done
force x distance moved in direction of force
explain the purpose of having the reservoir elevated higher than the rest of the power station
this allows the water to have a higher amount of gravitational energy that can be converted to kinetic energy when the water moves downwards to turn the turbine
explain why the lower part of the dam is thicker than the upper part
water pressure increases with depth. the thicker wall enables the dam to withstand the increase in water pressure exerted on the wall
