Phy Y10Y11 Y10 C2.3 C2.4 Acceleration 03

ACCELERATION

Acceleration is a vector quantity that is defined as the rate at which an object changes its velocity. An object is accelerating if it is changing its velocity.

Multiple Select

SELECT ALL THAT APPLY: Acceleration occurs when an object in motion . . .

• does not change its velocity or direction

• speeds up

• slows down

• changes direction

Multiple Choice

An airplane flying at the speed of 50 m/s slows down to 35 m/s in 5 seconds. What is the acceleration of the plane?

• -5 m/s²

• 5 m/s²

• -3 m/s²

• 3 m/s²

Multiple Select

SELECT ALL THAT APPLY: Acceleration occurs when an object in motion . . .

• does not change its velocity or direction

• speeds up

• slows down

• changes direction

Multiple Choice

An airplane flying at the speed of 50 m/s slows down to 35 m/s in 5 seconds. What is the acceleration of the plane?

• -5 m/s^2

• 5 m/s^2

• -3 m/s^2

• 3 m/s^2

Multiple Choice

Name the region with steady constant speed

• B, D and H

• A,C and G

• E

• F

Multiple Choice

Name the region that is stationary

• B, D and H

• A,C and G

• E

• F

Multiple Choice

Name the region that is slowing down

• B, D and H

• A,C and G

• E

• F

Multiple Choice

Name the region that is speeding up

• B, D and H

• A,C and G

• E

• F

EXAMPLES OF ACCELERATION

Acceleration could mean speeding up....that is the obvious one of course.

EXAMPLES OF ACCELERATION CONTINUED

Acceleration can also mean to SLOW DOWN! Yes....acceleration actually means any change in speed even if that means slowing down.

HERE IS THE WEIRDEST THING ABOUT ACCELERATION....

Acceleration not only means a change in speed (either speed up or slow down) it also means a change in DIRECTION.....Yes, when you go around a curve or turn one way or another even if you do it slowly you are considered accelerating!!!

Multiple Choice

A car is safely speeding up from 10 km per hour to 50 km per hour. what is the car doing?

• accelerating

• speeding

• stopping

Multiple Select

A car is slowing down from 50 km per hour to 20 km per hour...what is the car doing?

• accelerating

• decreasing speed

• decelerating

• constant speed

Multiple Choice

A car comes to a curve in the road and proceeds to safely follow the curve and keep on going...what did the car do in the curve even though it never changed its speed?

• the car accelerated by simply changing direction and keeping its speed the same

• the car simply turned...it has nothing to do with acceleration

Multiple Select

According to the video you just watched, What is the units for acceleration?

• m / s²

• Meters per second squared

• meters per second per second

• None of these are correct

Multiple Choice

If a car goes from zero to 50 meters/ second in 30 seconds, what is its acceleration?

• 1.7 meters / second squared

• 0.6 meters / second squared

Multiple Choice

If a car goes from 10 meters a second to 50 meters a second in 6 seconds, what is its acceleration? (remember to subtract the initial speed from the final speed to get your actual speed , v - u)

• 6.7 meters per second squared

• 0.15 meters per second squared

• 6.7 miles per hour

• 0.15 miles per hour

Multiple Choice

If an object is speeding up what is the value of the acceleration?

• positive acceleration means speeding up

• positive acceleration means slowing down

Multiple Choice

If an object is slowing down what is the value of acceleration?

• slowing down will give us a negative acceleration value

• slowing down will give us a positive acceleration value

examples of acceleration review

• speeding up is considered a positive acceleration

• slowing down is considered a negative acceleration

• changing direction could be either a negative or positive acceleration depending on the change that takes place

Calculating acceleration

Multiple Choice

$$\Delta v=45\ \frac{m}{s}$$  

$$t=5s$$   What is the acceleration of this system?

• $$9\ \frac{m}{s^2}$$  

• $$5\ \frac{m}{s^2}$$  

Multiple Choice

Which is the constant velocity?

• The sloping line at the start

• The horizontal part of the line

• The area under the line

• The sloping line at the end

Open Ended

(a) State the time when the ball reaches the start of the rough section of the horizontal surface.

Open Ended

(b) Explain how Fig. 1.1 shows that there is no resultant force on the ball when it rolls along the smooth section of the horizontal surface.

Open Ended

(c) Using Fig. 1.1, determine the acceleration of the ball as it rolls down the ramp.

Open Ended

(d) The ball starts from rest at the top of the ramp. Show that the length of the ramp is 9.6m