Motion and Force Chapter 1 Study Guide Answer Key

  1. If you are in a car and you start moving faster then your acceleration increases.
  1. Jake walks north at 2 miles per hour while Sara walks south at 2 miles per hour. Jake and Sara have the

same speeds but different velocities

  1. Velocity is speed in a specific direction
  1. Oliva runs 200 meters in 20 seconds, moving at different speeds. Calculate her average speed. (show your work)

S = d/tS = 200 m / 20 sS = 10 m /s

  1. Motion is a change in position over time.
  1. Acceleration measures a change in velocity
  1. You need to know both distance and time in order to calculate speed
  1. If your velocity stays the same then your acceleration is equal to zero
  1. Draw a line on each of velocity-time graphs to show the following:

Positive AccelerationNegative AccelerationNo Acceleration

Diagonal line from bottom left to top right

Diagonal line from top left to bottom right

Straight line across

  1. You need to know distance and time to calculate speed.
  1. Give an example of zero acceleration

(answers will vary, anything occurring at a steady rate)

  1. Velocity includes direction while speed does not.
  1. Find the average speed of an athlete that jogged 200 m in 25 seconds and then 100 m in 15 seconds. (please show your work)

Average Speed = total distance / total time

Average Speed = (200 m + 100 m) / (25 s + 15 s)

Average Speed = 300 m / 40 s = 7.5 m/s

  1. To find acceleration you subtract an object’s initial velocity from its final velocity and divide by the time it took to change velocity.
  1. What do you need to observe about an object in order to measure its motion?

You need to observe the objects position at different times.

  1. Maria started driving her car at a velocity of 30 mph west, then the speed limit increased and she

increased her velocity to 60 mph west. Maria’s trip showed positive acceleration.

  1. In order to calculate the time it will take to hike 10 miles, you need to know

the hiker’s average speed

  1. Latitude and longitude measure position
  1. How can you determine speed from a distance-time graph? Use the y-axis

to find the distance traveled and the x-axis to find the time.

Then use the formula S = d/t

  1. Describe how a car’s velocity and acceleration change when a driver applies the breaks and changes speed from 50 m/s to 45 m/s.

The car’s velocity decreased, and its acceleration became negative instead

of positive.

  1. What is a frame of reference? A frame of reference is a point from which

you observe motion.

  1. A bus goes from 20 m/s to 45 m/s in 5 seconds. What is the buses acceleration? (please show your work)

Acceleration = (final velocity – initial velocity) / time

A = (45 m/s – 20 m/s) / 5 s

A = 25 m/s / 5 s

A = 5 m/s2