Calculating Acceleration

 Our second (more complicated concept) in motion is to calculate acceleration:

Again, the first thing to keep in mind is to use SI units ("ms^-1" for the change in speed, and "s" for the time).

Note that we need to calculate the change in speed before we can calculate acceleration.

Calculating Speed from Acceleration

Sometimes, you will be asked to calculate the initial speed of something. This is one of the more difficult calculations using this equation.

For example,

When overtaking another driver, Sophie accelerates at 14.2 ms^-2 for 0.9s. She gets to a speed of 51.2 ms^-1. What speed was Sophie travelling at before she started to overtake the other driver?

STEP ONE: Calculate the change in speed

Δv    = a × Δt

        = 14.2 × 0.9

        = 12.78 ms^-1

STEP TWO: Calculate the initial speed

Δv    = final speed - initial speed

⇒ initial speed    = final speed - Δv

                            = 51.2 - 12.78

                            = 38.42 ms^-1

Calculating Speed

 Our first concept in the Motion topic is calculating speed:

The key thing to remember is to convert units into SI units (metres, m, for distance; seconds, s, for time; metres per second, ms^-1, for speed).

TIME, t

Units = seconds (s)

One minute = 60 seconds (multiply by 60 if you are given the time in minutes)

One hour = 3600 seconds (multiply by 3600 if you are given the time in hours)

DISTANCE, d

Units = metres (m)

1km = 1000m (multiply by 1000 if you are given the distance in kilometres))

100 cm = 1m (divide by 100 if you are given the distance in centimetres)

1000mm = 1m (divide by 1000 if you are given the distance in millimetres)

SPEED/VELOCITY, v

Units = metres per second (ms^-1)

1ms^-1 = 3.6km/h

If you are given a speed in km/h, you divide by 3.6 to get the answer in ms^-1.

If you have an answer in ms^-1 but want it in km/h, you multiply by 3.6.

SOURCE: https://www.tes.com/teaching-resource/animal-speed-calculations-6179689

Variation

In populations of any species, we observe variation - differences between individuals. Variation can be due to genetic inheritance, the environment, or a combination of both. Variation helps a species survive a change to its environment - individuals may (sadly) die, but enough members of the population/species should survive and breed.

This post has a selection of videos that cover how that variation comes about, and the results of such variation - natural selection.

Mutations

Asexual and Sexual Reproduction

Meiosis

Natural Selection