Forces and Motion Chapter 1

Question 1

define motion

Answer 1

an objects change in position relative to a reference point

Question 2

how can you describe the direction of an objects motion

Answer 2

using a reference direction

Question 3

define speed

Answer 3

distance traveled divided by the time during which the motion occured

Question 4

give an example of metric and english units used to measure speed

Answer 4

metric- meters/second english- miles/hour

Question 5

define velocity

Answer 5

the speed of an object in a particular direction

Question 6

how is velocity different from speed?

Answer 6

it’s the same as speed except velocity uses a reference direction

Question 7

what can be said about the velocity of an object that is in circular motion?

Answer 7

an object traveling in a circular motion is always changing direction, so it’s accelerating (centripetal acceleration)

Question 8

define force and give the unit

Answer 8

a push or a pull exerted on an object that changes the motion, expressed in newtons

Question 9

what is net force?

Answer 9

combination of all the forces acting on an onject

Question 10

how do you calculate net force when the forces are in the opposite direction?

Answer 10

add them together

Question 11

how do you calculate net force when the forces are in the opposite direction?

Answer 11

subtract the smaller force from the bigger one

Question 12

what is the net force when the forces are balanced?

Answer 12

0 newtons

Question 13

what occurs when forces are balanced?

Answer 13

will not cause a change in motion, will not cause a non-moving object to start moving

Question 14

what occurs when forces are unbalanced

Answer 14

produce a change in motion, will cause motionless object to start moving

Question 15

define friction

Answer 15

a force that opposes motion between two surfaces that are in contact

Question 16

how does force affect friction?

Answer 16

adding more force increases friction

Question 17

does a rough or smooth surface cause friction and why?

Answer 17

rougher surfaces have more friction because they have more hill/valleys in the surface that can come into closer contact

Question 18

what effect does surface area have on friction?

Answer 18

none

Question 19

what is the different between kinetic and static friction?

Answer 19

kinetic is friction between moving objects, static is when force is applied but does cause the object to move

Question 20

name examples of how friction can be harmful

Answer 20

• cause car parts part to heat up/wear down

- cause holes in socks/jeans

Question 21

name examples of how friction can be helpful

Answer 21

• allows pencil to leave a mark
• you would slip and fall w/out friction
• helps brakes stop a car

Question 22

how can you decrease friction?

Answer 22

• use lubricants
• make surfaces smoother
• switch from sliding kinetic friction to rolling kinetic friction

Question 23

how can you increase friction?

Answer 23

• make surfaces rougher

- increase force pushing surfaces together

Question 24

define gravity

Answer 24

force of attraction between objects what is due to their masses

Question 25

what two factors determine gravitational force

Answer 25

mass and distance

Question 26

define mass and weight

Answer 26

mass- amount of matter in an object

weight-measure of gravitational force exerted on an object