The Motion Of Usain Bolt 's 100 Metre Sprint

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Part a

This paper will examine the motion involved throughout Usain Bolt’s 100 metre sprint. To examine his motion it must be broken into three separate sections (Start – Middle – End).

Motion:
Motions are defined as the change in position of an object. According to the Columbian Electronic Encyclopedia “the rate of change is the speed of the body. If the direction of motion is also given, then the velocity of the body is determined.” (Columbian Encyclopedia, 1993).

Usain Bolt:
Time (100m Sprint): 9.58 seconds
Weight: 94 kg
Height: 1.95 metres
Distance: 100 metres

Start

The start of Usain Bolt’s sprint will be referred to as the first 0 – 10 metres of the track.
Segment (m) Time (s)
0-10 1.85
10-20 1.02
20-30 0.91

Newton’s 3rd Law can be stated as follows:
For every action there is an equal and opposite re-action. Usain is motionless on the blocks. When he kicks off the blocks, which is the action. Whenever he kicks off the blocks, the blocks move backwards. That is the equal and opposite reaction.

Velocity is how fast the object moved, and in which direction it’s progressed. Velocity is often measured in metres per second (ms-1). So the velocity calculated for v= s/t

v=10/1.85

v=5.46 ms-1 v=19.67 km/h

The acceleration of an object is the change in velocity. Acceleration is measured in metre per second (ms-2). The acceleration of Usain Bolts 0-10 metres start in his sprint is:
S = at+1/2 at2 is rearranged to a= 2s/(t (t+2)) a= 20/(1.85(1.85+2))

a=2.80 ms-2

Displacement is the first zero to ten metres of the sprint.

MIDDLE

The middle (or half way point) of Usain Bolt’s sprint will be referred to as the first 40 – 50 metres of the track.
Segment (m) Time (s)
0-10 1.85
10-20 1.02
20-30 0.91
30-40 0.87
40-50 0.85
50-60 0.82
60-70 0.82
70-80 0.82
80-90 0.83
90-100 0.90

Newtons 1st Law is applied into the middle segment of the sprint, as this is where Usain is at his fastest point. Bolt is in motion and wants to remain in motion however air resistance and gravity are both pulling against his body, producing drag to his sprint. At this point of the sprint there is nothing at rest, therefore everything must stay in