Question

part b identify the forces exerted on the ball from the time the ruler touches it.

Explanation:

When the ruler touches the ball, the forces on the ball are: 1. Applied Force (from the ruler): The ruler exerts a contact force on the ball as it touches, causing a push or pull. 2. Gravitational Force (Weight): The Earth pulls the ball downward with a force \( F_g = mg \) (where \( m \) is mass, \( g \) is acceleration due to gravity). 3. Normal Force (if on a surface): If the ball is on a surface (like a table), the surface exerts an upward normal force balancing gravity (or part of it, depending on context). 4. Frictional Force (if applicable): If there's relative motion or tendency between the ruler/ball or ball/surface, friction (e.g., kinetic or static friction) acts. For a typical scenario with a ball on a surface and ruler pushing, the main forces are applied (ruler), gravitational, normal (surface), and possibly friction (between ball and surface, or ball and ruler).

Answer:

The forces exerted on the ball are:

• Applied Force (from the ruler, a contact force causing motion/change in motion).
• Gravitational Force (weight, pulling the ball downward, \( F_g = mg \)).
• Normal Force (from the supporting surface, upward, balancing gravity if the ball is on a surface).
• Frictional Force (if there is relative motion or tendency, e.g., between the ball and the surface or the ball and the ruler, opposing motion).

(For a simplified case, e.g., ball on a horizontal surface being pushed by the ruler: applied force (ruler), gravitational force (downward), normal force (upward from surface), and kinetic friction (opposing the ball’s motion relative to the surface) if the ball moves.)