1D KINEMATICS AP Physics 1

KINEMATICS How objects move

2.1 REFERENCE FRAMES AND DISPLACEMENT

REFERENCE FRAME Any measurement of position, distance, or speed is made in respect to the frame of reference (background)

DISPLACEMENT (ΔX) Change in position of the object Units = meters (m) Displacement is NOT the same as distance

VECTORS Quantities that have both magnitude and direction Ex: Displacement + vector = points to the right - vector = points to the left

DISPLACEMENT VECTOR

AVERAGE SPEED Average Speed = Distance traveled Time

VELOCITY

INSTANTANEOUS VELOCITY

ACCELERATION

CONSTANT ACCELERATION

PROBLEM SOLVING 1.Write down givens and unknowns 2.Check units 3.Pick an equation 4.Plug in numbers and solve 5.Box your answer

FREE FALL Acceleration due to gravity a = g = 9.8 m/s 2 + g = downward - g = upward (decelerating) Vector

GALILEO’S HYPOTHESIS All objects would fall with the same constant acceleration in the absence of air or other resistance.

AP PHYSICS 1 DAY 10 OBJECTIVE Know: The definition of free fall. Understand: How to use the BIG 4 to find x, v, or t during free fall. Do: Find the maximum height of a rocket using the BIG 4. WARMUP Eli Manning Question

3.1 VECTORS AND SCALARS Scalar – a quantity that can be completely defined by magnitude “how much” Time, weight, height, volume, speed, density, temperature, etc. “size” matters Vector – a quantity that can be defined by magnitude and direction Velocity, momentum, acceleration, displacement, force

PROPERTIES OF VECTORS 1.Vectors can be moved parallel to themselves 2.Vectors can be added in any order 3.Vectors can be divided into components

ADDING VECTORS: TIP TO TAIL 1.Draw one of the vectors to scale 2.Draw the second vector to scale, placing its tail at the tip of the first vector. 3.The arrow drawn from the tail of the first vector to the tip of the second is the sum or resultant

ADDING VECTORS: PYTHAGOREAN THEOREM Can only be used for right triangles to find the resultant.

PROJECTILE MOTION RULES 1.All objects fall at a rate of 9.8 m/s 2 2.Unless you have wings, jet propellers, rockets etc. your x motion is independent of your y motion (never cross) 3.Ignoring air resistance a x = 0 m/s 2 a y = 9.8 m/s 2

PROJECTILE PROBLEM SOLVING 1.Separate problem into x and y. 2.Write down givens and unknowns 3.Draw and label a picture 4.Make time the “cross over” 5.Use the column with only 1 unknown to solve for time 6.Cross over time and solve

GALILEO An object projected horizontally will reach the ground in the same time as an object dropped vertically.

HORIZONTAL RANGE (R)

RELATIVE MOTION 1.Draw a diagram 2.Label each velocity with two subscripts 1.Refers to the object 2.The reference frame in which it has this velocity CHECK to make sure the inner subscripts on the right hand side are the same, and the outer subscripts are the same as the two subscripts on the left.