When jumping straight up from a crouched position, an average person can reach a maximum height of about 60 cm. During the jump, the person's body from the knees up typically rises a distance of around 50 cm. To keep the calculations simple and yet get a reasonable result, assume that the entire body rises this much during the jump. (b) Draw a free-body diagram of the person during the jump.

Verified step by step guidance

1. Identify the forces acting on the person during the jump. These include the gravitational force acting downwards and the normal force exerted by the ground acting upwards.
2. Draw a vertical line to represent the person. This line will help in aligning the forces accurately.
3. At the bottom of the line (representing the feet of the person), draw an arrow pointing upwards. Label this arrow as the normal force (N), which is the force exerted by the ground.
4. From the center of the line (representing the center of mass of the person), draw an arrow pointing downwards. Label this arrow as the gravitational force (mg), where m is the mass of the person and g is the acceleration due to gravity.
5. Ensure that the length of the arrows roughly indicates the magnitude of the forces. Since these forces are equal and opposite when the person is just about to leave the ground, the arrows should be of equal length.

Key Concepts

Free-Body Diagram

A free-body diagram is a graphical representation used to visualize the forces acting on an object. In the context of a person jumping, it illustrates all the forces, such as gravity and the force exerted by the ground, acting on the jumper at a specific moment. This helps in analyzing the motion and understanding how these forces influence the jump.

Forces in Motion

Forces in motion refer to the interactions that cause an object to accelerate or change its velocity. In a jump, the primary forces include gravitational force pulling the person downward and the upward force generated by the legs pushing against the ground. Understanding these forces is crucial for analyzing the dynamics of the jump.

Kinematics

Kinematics is the branch of physics that deals with the motion of objects without considering the forces that cause the motion. It involves concepts such as displacement, velocity, and acceleration. In the context of the jump, kinematics helps describe how high the person rises and the time taken to reach that height, providing a framework for understanding the jump's trajectory.