chp 9 : application of forces and transfer of energy

Question 1

what is forces

Answer 1

a push or pull

Question 2

what is the SI unit of forces

Answer 2

newton (N)

Question 3

what do we have to state when describing forces

Answer 3

magnitude and direction (20N downwards)

Question 4

what are contact forces

Answer 4

frictional force and tension

Question 5

what are non contact forces

Answer 5

magnetic forces and gravitational force

Question 6

what are frictional forces

Answer 6

a force that opposes 2 surface in contact

Question 7

which direction does friction act in

Answer 7

opposite of motion
rollers/ball bearings -> same direction as motion

Question 8

the ___ the surface, the ___ the heat generated
(frictional force)

Answer 8

the rougher the surface, the greater the heat generated

Question 9

what does friction depend on

Answer 9

the nature of the surface and the weight of the body , not the size

Question 10

how can friction be reduced

Answer 10

lubricant, ball bearings and rollers

Question 11

what is tension

Answer 11

tension resists an elastic object’s change in shape

Question 12

what direction is tension exerted in

Answer 12

opposite direction of how the object is stretched

Question 13

what is magnetic force

Answer 13

the force exerted between a magnet and magnetic material

Question 14

what is gravitational force

Answer 14

an attraction force btwn 2 masses

Question 15

the ___ the mass, the ___ the force
(gravitational force)

Answer 15

the larger the mass, the larger the force

Question 16

what is gravitational force also known as

Answer 16

weight

Question 17

what do we use to measure a pulling force

Answer 17

spring balance

Question 18

what do we use to measure weight (gravitational force)

Answer 18

spring balance / compression spring balance

Question 19

what is mass measured with

Answer 19

calibrated electronic balance, beam balance

Question 20

what is the formula to find gravitational field strength

Answer 20

w=mg

Question 21

what are the effects of forces

Answer 21

speed, direction, size/shape, pressure

Question 22

what is moment

Answer 22

a force about a pivot is called the moment of force

Question 23

____ force, ____ moment
(moment)

Answer 23

larger force, larger moment

Question 24

____ perpendicular distance, ____ moment
(moment)

Answer 24

larger perpendicular distance, larger moment

Question 25

what is the formula for pressure

Answer 25

pressure = force/contact

Question 26

____force, ___ pressure (pressure)

Answer 26

the larger the force, the larger the pressure

Question 27

___ contact area, __ pressure (pressure)

Answer 27

the larger the contact area, the smaller the pressure

Question 28

SI unit for pressure

Answer 28

Pa

Question 29

the unit for pressure

Answer 29

N//m2

Question 30

amount of ___ = amount of ___ (pressure)

Answer 30

amount of force = amt of weight

Question 31

the water pressure ____ as the depth ___

Answer 31

the water pressure increases as the depth increases

Question 32

___ altitude, ___ atmospheric pressure

Answer 32

higher altitude, lower atmospheric pressure

Question 33

describe the atmospheric pressure of drinking straw

Answer 33

as we inhale the water, the air pressure in the straw becomes lower atmospheric pressure in the cup pushing the water into the straw has a higher air pressure, hence it pushes the water upwards into the straw

Question 34

what does work done mean

Answer 34

force is applied to the object and the object moves in the same direction as force applied

Question 35

SI unit of energy

Answer 35

joule (J)

Question 36

what is energy

Answer 36

the ability to do work

Question 37

what can energy not do

Answer 37

energy cnt be destroyed or created, it can only be converted

Question 38

what is potential energy

Answer 38

stored energy

Question 39

what is chemical potential energy

Answer 39

energy stored in chemical bonds of a substance

Question 40

what is elastic potential energy

Answer 40

energy stored in an elastic object that is stretched, compressed, deformed

Question 41

what is gravitational potential energy

Answer 41

energy stored in an object bcos of its position or height above earth's surface

Question 42

formula for gravitational potential energy

Answer 42

gpe = mgh

Question 43

what is kinetic energy

Answer 43

energy an object has bcos of motion

Question 44

as mass and speed ____, KE ____

Answer 44

as the mass and speed increase, ke increases

Question 45

formula for ke

Answer 45

1/2mv2