our dynamic universe

Question 1

newtons 1st law

Answer 1

object will remain at rest or at constant speed in straight line unless acted on by an unbalanced force

Question 2

newtons 2nd law

Answer 2

when forced acting on an object are unbalanced, objects will accelerate in direction of unbalanced force

F= ma

Question 3

newtons 3rd law

Answer 3

if object A exerts force on object B, then B exerts equal but opposite force on A

Question 4

equation for weight, mass, and gravity

Answer 4

W= mg

Question 5

weight parallel to slope formula

Answer 5

W= mgsinθ

Question 6

weight perpendicular to slope formula

Answer 6

W= mgcosθ

Question 7

equating energy work to potential and kinetic

Answer 7

Ew= Ep-Ek

Question 8

equation for lifting object from ground

Answer 8

Ew= Ep

Question 9

conservation of momentum formula

Answer 9

m₁u₁ + m₂u₂ = m₁v₁ + m₂v₂

Question 10

what is the doppler effect?

Answer 10

change in frequency observed when a source of sound, or light, waves move relative to an observer

Question 11

what happens when sound approaches an observer?

Answer 11

more sound waves received per sec (shorter wavelength)

frequency heard increased

Question 12

what happens when sound moves away from an observer?

Answer 12

fewer sound waves received per sec (longer wavelength)

frequency heard decreased

Question 13

what is redshift?

Answer 13

light from stars or galaxies moving away from us is shifted to longer (more red) wavelengths

Question 14

what does a negative redshift value mean?

Answer 14

blueshift

Question 15

how to calculate distance in light years?

Answer 15

distance/ 1 light year

Question 16

how to calculate 1 light year?

Answer 16

365x24x60x60 (3x10⁸)

Question 17

current estimate for age of universe

Answer 17

13.8 billion

Question 18

what is dark matter?

Answer 18

matter in galaxies we cant see

Question 19

evidence for dark matter

Answer 19

stars on outer arms of galaxies should travel slower than those closer to galactic core as they are further from centre of mass and experience smaller gravitational force of attraction

observations found orbital speed of stars on these parts to be moving much faster than expected for the mass that is visible to us

Question 20

what is dark energy?

Answer 20

recent observations of redshift of distant galaxies shows universes rate of expansion is increasing

this contradicts idea that gravity is an unbalanced force acting to slow expansion down

-suggests unknown force acting against gravitation attraction, pushing matter apart

Question 21

what is the big bang theory?

Answer 21

rapid expansion from a singularity

Question 22

6 pieces of evidence for big bang theory

Answer 22

hubbles law

cosmic microwave background radiation

temperature of universe

surface temperature

olbers paradox

larger number of galaxies showing redshift than blueshift

Question 23

gravitational force of attraction

Answer 23

6.67x10-¹¹