Reviewing Main Ideas Describing Motion Motion is a change of position of a body. Distance is the measure of how far an object moved. Displacement is the distance and direction of an object's change in position from the starting point. A reference point must be specified in order to determine an object's position.

Reviewing Main Ideas Describing Motion The speed of an object can be calculated from this equation: The slope of a line on a distance-time graph is equal to the speed. Velocity describes the speed and direction of a moving object.

Reviewing Main Ideas Velocity and Momentum Velocity describes the speed and direction of a moving object. Momentum is the product of an object’s mass and velocity.

Reviewing Main Ideas Acceleration Acceleration occurs when an object changes speed or changes direction. An object speeds up if its acceleration is in the direction of its motion. An object slows down if its acceleration is opposite to the direction of its motion. Acceleration is the rate of change of velocity, and is calculated from this equation:

Chapter Review Question 1 Which includes both the speed of a moving object and the direction of its motion? A. displacement B. distance C. instantaneous speed D. velocity

Chapter Review Answer The answer is D. Displacement includes direction, but not speed.

Chapter Review Question 2 What is the average speed in m/s of a runner who travels 10.0 km in 1.5 hours? A. 6.67 m/s B. 1.85 m/s C. 0.93 m/s D. 0.85 m/s

Chapter Review Answer The answer is B. Remember to convert kilometers to meters and hours to seconds.

Chapter Review Question 3 A car travels at a constant speed of 40 m/s for 2 hours. What was the distance traveled in km?

Chapter Review Answer The car traveled 288 km. There are 3,600 s in 1 h and 1,000 m in 1 km. Step 1: 40 m/s × 7,200 = 288,000 Step 2: 288,000= 288 km 1,000

Standardized Test Practice Question 1 A moving object traveled 4900 m in 165 s. What is its average speed? A. 165 m/s B. 55 m/s C. 30 m/s D. 15 m/s

Standardized Test Practice Answer The answer is C. Average speed is equal to the total distance traveled divided by the total time of travel.

Standardized Test Practice Question 2 This graph represents swim times for three different swimmers. Which swimmer did not maintain a constant speed?

Standardized Test Practice A. A B. B C. C D. All speeds were constant.

Standardized Test Practice Answer The answer is C. During the time interval between 10 and 20 minutes, swimmer C had a speed of 0 m/min.

Standardized Test Practice Question 3 Calculate the acceleration of a car that starts at rest and has a final velocity of 30 m/s north after 10 s. A. 3 m/s2 South B. 3 m/s2 North C. 20 m/s2 South D. 20 m/s2 North

Standardized Test Practice Answer The answer is B. Use this equation to calculate acceleration: a = (vf – vi)/t

Standardized Test Practice Question 4 Car A is traveling north at 85 km/h. After 1 hour, the car turns around 180º and travels at the same speed for 1.5 hours. What is the car’s displacement at the end of the trip? A. 42.5 km South B. 127.5 km South C. 212.5 km South D. 42.5 km North

Standardized Test Practice Answer The answer is A, 42.5 km South. During the first hour the car traveled 85 km North. During the second hour, the car traveled 127.5 km South. Even though the total distance traveled is 212.5 km, the car is 42.5 km South of its starting point.

Standardized Test Practice Question 5 What is Bill’s average speed? Runner Distance (km) Time (min) Carlos 14.5 42 Bill 8.0 38 Janet 12.4 32 Ann 10.3 30

Standardized Test Practice A. .10 km/min B. .21 km/min C. .34 km/min D. .38 km/min Runner Distance (km) Time (min) Carlos 14.5 42 Bill 8.0 38 Janet 12.4 32 Ann 10.3 30

Standardized Test Practice Answer The correct answer is B. Use the equation: