IB Sports, exercise and health science B.2.1 Newton’s Laws of Motion Questionbank

(a) Refer to Figure 1. Identify the time interval during which the sprinter's acceleration is greatest.

(b) Refer to Figure 1. Describe the trend in velocity and what this indicates about the sprinter's acceleration.

(c) Using Newton's second law (F = ma), explain why the net horizontal force on the sprinter must have decreased over the 1-second period.

(d) Refer to Table 1. Explain how impulse determines the change in the sprinter's velocity during the start phase.

What concept is illustrated when a gymnast pushes down on a trampoline and it propels her upward?

An Olympic weightlifter applies a constant upward force of $1750\text{ N}$ to a barbell with a mass of $140\text{ kg}$. Take $g=10\text{ m s}^{-2}$, so the weight of the barbell is $1400\text{ N}$. What is the magnitude of the barbell's acceleration at the instant the force is applied?

Skill B reached a higher peak centre of mass displacement, indicating a greater vertical take-off velocity/impulse

Skill A demonstrates superior technique due to reduced energy expenditure

Skill B shows reduced flight time and greater control in rotational phases

Skill A maintains longer aerial time, indicating better stability and balance

Hard Court

Grass

Sand

All surfaces show equal decrease in momentum

A sports science lab analysed the first second of the sprint start for an elite 100 m sprinter of mass 80 kg. A force plate and motion capture recorded the sprinter's horizontal velocity and the net horizontal force acting on them every 0.2 s. The data are shown in Figure 1 and Figure 2. The impulse for each 0.2 s interval was calculated as the area under the force–time graph, and is shown in Table 1.

Figure 1: Horizontal velocity of the sprinter over the first second

Figure 2: Net horizontal force on the sprinter over the first second

Table 1: Impulse during each 0.2 s interval