Transcript Acceleration - Sikeston R-6

Teacher Page
•IV. Force, motion and mechanical energy
•A. Relative Motion
•7th grade assessment
•Science standards 3.1; 3.3; 4.1
•Students should be able to explain how an object’s acceleration is
affected by outside forces and its mass.
•View lesson before using with students. Click mouse to view
sample questions and answers.
What is acceleration?
• Increasing speed.
• Decreasing speed.
• Changing direction.
In your journal describe the
acceleration of a race car as it runs the
race course.
• Increasing speed - When the car begins to
move from a stopped position or speeds up
to pass another car.
• Decreasing speed - When the car stops at
the pit or slows down for a yellow flag.
• Changing direction - When the car enters a
curve or changes lanes.
Calculating Acceleration
• A roller coaster picks up speed as it rolls down the
slope, its speed is 4 m/s. But 3 seconds later, at the
bottom its speed is 22 m/s. What is its average
acceleration?
• Analyze: You know the initial velocity and final
velocity of the car, and the length of time during
which its velocity changed. You are looking for its
acceleration.
• Write the formula:
Acceleration = Final velocity - Initial velocity
Time
Calculating Acceleration
• A roller coaster picks up speed as it rolls
down the slope, its speed is 4 m/s. But 3
seconds later, at the bottom its speed is 22
m/s. What is its average acceleration?
• Substitute and solve:
• Acceleration = 22 m/s - 4 m/s
3s
• Acceleration = 18 m/s = 6 m/s2
3s
Practice Problem
• An eagle accelerates from 15 m/s to 22 m/s
in 4 seconds. What is the eagle’s average
acceleration?
• Acceleration = 22 m/s - 15 m/s
4s
• Acceleration =