AKS 8a: Speed, Velocity, and Acceleration (

AKS 8A: Speed, Velocity and Acceleration

By Marissa Brown

Speed, Velocity, & Acceleration

How are they different?

Learning Objective

• Know what speed, velocity, and acceleration are.

• Understand how they are different

• Be able to calculate speed, distance, time, and acceleration

Speed

• Speed is the measure how quickly distance changes with time.

• There are two types of speed: average speed and instantaneous speed.

• Average speed can be found by taking the total distance dividing by total time of travel

• Instantaneous speed is the speed of the object at the specific instant in time.

• Units for speed include mph with SI unit being m/s.

Multiple Choice

Find the speed of Ms. Chen after 40 sec at 8 meters.

• 5m/s

• 8m/s

• 5 mph

• 40 mph

Using Equations to Solve for Speed, Distance, & Time

• Distance = speed x time

• Time = distance / speed

• Speed = distance / time

Multiple Choice

The average speed on 933 is 60mph and it is 30 miles from Whitney to Cleburne. How long will it take to get to Cleburne if I leave at 4pm?

• 5min

• 30 min

• 5hrs

• 30 sec

Velocity

• Velocity of an object is its speed combined with the direction of the motion

• Just add the direction to the speed and you have velocity

• An example ofvelocity would be 70mph south

Vector vs Scaler Quantity

• Velocity is a vector quantity while speed is a scaler quantity

• Vector quantity is a physical quantity that has both size and direction

• Scaler quantity is singular, size or direction.

Multiple Select

Check the correct examples of velocity

• 6km/h

• 4 km/h north

• 70mph

• 70mph east

• 25 feet up

Acceleration

• Acceleration is a measure how quickly velocity changes.

• Acceleration describes the change in velocity over time.

• The SI unit for acceleration is m/s^2

Multiple Choice

Caiden is running down the field at first going 15m/s then after 20 sec is going 30m/s. What is his acceleration?

• .75 mph

• 2m/s

• 0.75m/s² south

• 2mph

Multiple Select

How are speed and velocity different?

• Velocity has direction plus speed

• Speed is scaler while velocity is vector

• change in position

• one is normal and one is weird

Acceleration

• Can be negative (deacceleration)

• Goes in opposite direction of velocity

Multiple Choice

A runner whose initial speed is 8 m/s increases her speed to 9 m/s in order to win a race. If the runner takes 5.0 s to complete this increase in speed, what is her acceleration?

• 0.2 m/s²

• -0.2 m/s²

• 5 m/s²

• -5 m/s²

Multiple Choice

The formula d/t is used for calculating ______________ and _________________.

• Speed and velocity

• Speed and acceleration

• speed and average speed

Multiple Choice

What is the unit for speed? ____________

• m/s

• d/t

• m/s2

Multiple Choice

Which of the following describes the velocity of an object?

________________

• 50m/s

• 50 m east

• 50 m/s east

Multiple Choice

What is the difference between velocity and speed of an object?

• Velocity is the change in distance over time, while speed is the velocity over time.

• Velocity has a direction associated with it while speed has no specific direction.

• Velocity is the change in speed over time, while speed is the change in distance over time.

Multiple Choice

Acceleration is measured in ______________ units?

• m/s2

• m/s

• Mph

Multiple Choice

Acceleration on a distance time graph shows up as a _____________ line.

• straight diagonal

• straight horizontal

• curved

Multiple Choice

Speed on a distance time graph shows up as a straight ____________________ line.

• straight diagonal

• straight horizontal

• straight vertical

Multiple Choice

What is the formula for calculating average speed?

• Distance = speed divided by time

• average speed = total distance divided by total time

• velocity times speed = average speed

Multiple Choice

A base ball is hit 300 yards in 10 seconds. What is the speed of the baseball?

• 300 yards

• 10 yards

• 30 yards

Multiple Choice

Mr. Johnson is traveling from Sweeny, TX to San Antonio, TX. It takes 4 hours to make the 224 mile trip. What is his velocity.

• 56 mph North or Northwest

• 65 mph North

• 56 mph North

• 65 mph westnorth

Multiple Choice

Change in distance over a specific amount of time (speed) plus direction.

• velocity

• speed

• acceleration

Multiple Choice

What are two ways an object can accelerate without speeding up?

• Change directions or stop

• stop and then go

• change direction or slow down

Multiple Choice

A fighter jet lands on the flight deck of an aircraft carrier. The jet must reduce its speed from about 42.5 m/s to exactly 0 m/s in 2.0 s. What is the jet’s acceleration?

• 21.3 m/s²

• -21.3 m/s²

• 85 m/s²

• -85 m/s²

Multiple Choice

A bicyclist accelerates at 0.89 m/s² during a 5.0 s interval. What is the change in the speed of the bicyclist and the bicycle?

• 0.18 m/s

• 4.5 m/s

• 5.6 m/s

Multiple Choice

A freight train begins braking as it approaches a train yard. The train’s acceleration while braking is –0.33 m/s² . What is the change in the train’s speed after 23 s?

• -10.4 m/s

• 10.4 m/s

• 7.6 m/s

• -7.6 m/s

Multiple Choice

A child sleds down a steep, snow-covered hill with an acceleration of 2.82 m/s² . If her initial speed is 0.0 m/s and her final speed is 15.5 m/s, how long does it take her to travel from the top of the hill to the bottom?

• 5.5 s

• 0.19 s

• 42 s

• 8 s

Multiple Choice

The “street” automobile with the greatest acceleration is the Tempest. It has an acceleration of 6.89 m/s² . Suppose the car accelerates from rest to a final speed of 27 m/s. How long does it take the Tempest to reach this speed?

• 3.9 s

• 0.25 s

• 186 s

• 8.1 s

Multiple Choice

A certain type of rocket sled is used to measure the effects of sudden, extreme deceleration.

What is the acceleration of the sled reaches when its velocity changes from 90 m/s and then comes to a complete stop in 0.18 s.

• 500 m/s²

• -500 m/s²

• 16.2 m/s²

• -16.2 m/s²

Multiple Choice

A dog runs on a waxed floor at an initial speed of 1.5 m/s. It slides to a stop with an acceleration of –0.35 m/s² . How long does it take for the dog to stop?

• 3.3 s

• 0.53 s

• 0.23 s

• 4.3 s

Multiple Choice

The fastest elevators in the world accelerate upwards at 3.125 m/s². What is the change in speed of this elevator during a 4 second interval?

• 1.28 m/s

• 0.78 m/s

• 12.5 m/s

• 7.7 m/s