C H A P T E R 2 Kinematics in One Dimension

Mechanics The study of Physics begins with mechanics.

Mechanics The study of Physics begins with mechanics. Mechanics is the branch of physics that focuses on the motion of objects and the forces that cause the motion to change.

Mechanics The study of Physics begins with mechanics. Mechanics is the branch of physics that focuses on the motion of objects and the forces that cause the motion to change. There are two parts to mechanics: Kinematics and Dynamics.

Mechanics The study of Physics begins with mechanics. Mechanics is the branch of physics that focuses on the motion of objects and the forces that cause the motion to change. There are two parts to mechanics: Kinematics and Dynamics. Kinematics deals with the concepts that are needed to describe motion, without any reference to forces. Chapter 2: Kinematics in one dimension Chapter 3: Kinematics in two dimensions

Mechanics The study of Physics begins with mechanics. Mechanics is the branch of physics that focuses on the motion of objects and the forces that cause the motion to change. There are two parts to mechanics: Kinematics and Dynamics. Kinematics deals with the concepts that are needed to describe motion, without any reference to forces. Chapter 2: Kinematics in one dimension Chapter 3: Kinematics in two dimensions Dynamics deals with the effect that forces have on motion. Chapter 4: Dynamics

Distance and Displacement

Starting from origin, O a person walks 90-m east, then turns around and walks 40-m west.

Distance and Displacement Starting from origin, O a person walks 90-m east, then turns around and walks 40-m west. Q: What is the total walked distance?

Distance and Displacement Starting from origin, O a person walks 90-m east, then turns around and walks 40-m west. Q: What is the total walked distance? A: 130-m

Distance and Displacement Starting from origin, O a person walks 90-m east, then turns around and walks 40-m west. Q: What is the total walked distance? A: 130-m Q: What is the displacement?

Distance and Displacement Starting from origin, O a person walks 90-m east, then turns around and walks 40-m west. Q: What is the total walked distance? A: 130-m Q: What is the displacement? A: 50-m, due east.

Displacement The displacement Δx is a vector that points from the initial position to the final position. SI Unit of Displacement: meter (m)

2.2 Speed and Velocity Average Speed Average Velocity Instantaneous Velocity Instantaneous Speed

Average Speed Units for speed: m/s, MPH, kmPH.

Average Velocity Units for velocity: m/s, MPH, kmPH.

Instantaneous Velocity and Speed The instantaneous velocity v indicates how fast an object moves and the direction of the motion at each instant of time. The magnitude of the instantaneous velocity is called the instantaneous speed, and it is the number (with units) indicated by the speedometer.

Acceleration

Units: m/s 2, cm/s 2

Instantaneous acceleration Acceleration at a particular instant is called instantaneous acceleration.

Deceleration

An object speeds up when the acceleration and velocity vectors point in the same direction.

Deceleration An object speeds up when the acceleration and velocity vectors point in the same direction. Whenever the acceleration and velocity vectors have opposite directions, the object slows down and is said to be “ decelerating. ”

Deceleration An object speeds up when the acceleration and velocity vectors point in the same direction. Whenever the acceleration and velocity vectors have opposite directions, the object slows down and is said to be “ decelerating. ” Example 4: A drag racer crosses the finish line, and the driver deploys a parachute and applies the brakes to slow down. The driver begins slowing down when t 0 = 9.0 s and the car's velocity is v 0 = +28 m/s. When t = 12.0 s, the velocity has been reduced to v = +13 m/s. What is the average acceleration of the dragster?

Kinematics Equations