Velocity and Acceleration Notes

Velocity and Acceleration Notes

Unit 4 Notes

Open Ended

What is the difference between speed and velocity?

Velocity

includes the speed of an object and the direction of its motion.

Poll

Which of these would you say is what happens during acceleration?

• An object's motion increases in velocity

• An object's motion decreases in velocity

• An object's motion increases in speed and/or changes direction

• An object's motion decreases in speed and/or changes in direction

Acceleration is

the rate of change in velocity; acceleration occurs when there is a change in an object's speed, direction, or velocity.

How to calculate Acceleration:

Acceleration (meters/second2) =
change in velocity (meters/second) / time (seconds)

*Note: A change in velocity = final velocity - initial velocity

 $\Delta v=v_f-v_i$  

Positive Acceleration

Example: An airplane takes off...

a=v_f-v_i/t = (80m/s - 0m/s)/20s

a=4m/s²

The plane is speeding up so the acceleration is positive

Negative Acceleration

Example: A bike comes to a stop

a= (v_f-v_{i)/t = (0m/s - 3m/s)/2s}

_{a= -1.5m/s}²

The bike is slowing down so acceleration is negative

Multiple Choice

At what speed would a car have to move in order to travel 20 kilometers in 2 hours.

• 5 km/hr

• 10 km/hr

• 20 km/hr

• 40 km/hr

Multiple Choice

What is your acceleration if you are riding your bike at 9 km/hr, and 10 minutes later your speed is 6 km/hr.

• 0.3 km/hr

• 30 km/hr

• 0.3 km/hr/hr

• 300 km/hr

Multiple Choice

You are riding your bike at 9 km/h. Ten minutes later, your speed is 6 km/h.

• Acceleration occurred because speed increased.
• Acceleration occurred because speed decreased.
• Acceleration occurred because you changed directions.

Multiple Choice

A helicopter flies west 200 miles in 2 hours. What is its velocity?

• 99 mph

• 100 mph south

• 400 mph south

• 297 mph south

Multiple Choice

A stopped car begins moving and reaches a speed of 25m/s in 5 seconds. What is its acceleration?

• +25m/s²

• -0m/s²

• +5m/s²

• 5m/s

Multiple Choice

Find the velocity of a plane that traveled 3000 miles west in 5 hours.

• 65 mph

• 600 mph

• 600 mph west

• 600 mph

Multiple Choice

65mi/hr South is an example of...

• Speed
• Velocity
• Acceleration
• Direction

Multiple Choice

Avery likes to walk 30 feet in 10 seconds. What is her speed?

• 3 feet/sec
• 6 feet/sec
• 10 feet/sec
• 2 feet/sec