Final answer:
An unbalanced force can be seen when an athlete serves a volleyball as it creates a net acceleration. Various forces act on objects in motion, including gravitational, contact, and field forces, affecting their trajectories.
Step-by-step explanation:
An example of an unbalanced force comes into play when an athlete is serving a volleyball. In this scenario, the volleyball is initially stationary and the force applied by the athlete’s hand to the ball causes it to accelerate, indicating that the forces are not in balance. On the other hand, a computer on a table, a man leaning against a wall, and fruit in a bowl represent situations where forces are balanced, as there is no net acceleration occurring.
Considering forces acting on moving objects, several factors can contribute:
- (a) For a soccer ball being kicked, the most common forces at play include the kick applied by the soccer player (a direct push), along with gravity, air resistance (friction), and occasionally the ground responding to the ball's motion.
- (b) When a dolphin jumps, it exerts a force on the water through its muscles, while gravity and water resistance affect its motion.
- (c) A parachutist drifting to Earth is influenced mainly by gravity, but also experiences significant air resistance which slows the descent.