A tennis player practices serving toward an elevated platform, simulating pressure shots into corners of the court or elevated targets (Figure 1). Motion capture and performance analysis software were used to record flight trajectory, clearance height, and recovery time across different launch angles (Table 1). The aim was to understand how varying launch angles impact performance trade-offs, including net clearance, ball height, and time available for recovery.

Table 1: Performance Characteristics at Different Launch Angles

A javelin thrower is analysing her technique with her coach. The figure shows how the range of a projectile depends on its release speed, when it is thrown at a fixed angle. Table 1 shows data recorded from one of her throws.

Figure: Range against release speed

Table: Data from one of her throws

A soccer player kicks a ball with a significant side-spin, causing it to curve in flight. Which statement best explains why the ball follows a curved trajectory?

Why does a swimmer float more easily in the ocean than in a freshwater pool?

Which of the following statements about viscosity is true?