Intro to Kinematics

​Introduction to

​Kinematics

​Mr. Cascabel

​Kinematics

​As physics try to study the fundamental parts of the universe in terms of relationship of matter and energy, one of its branches focus on describing motion – kinematics.

​

Kinematics describes the motion of objects based on a specific frame of reference. It describes its velocity, acceleration, displacement and amount of time it travelled.

​

In describing motion, it is very important to convert units and apply rules on significant figures. ​

Multiple Choice

Which branch of Physics deals with describing motion?

• Kinematics

• Acoustic

• Thermodynamics

• Mechanics

Multiple Choice

Which of the following is physics concerned about?

• relationship of matter and energy

• truth about life after death

• morality and justice

• aesthetics i design

Multiple Choice

Which of the following is NOT a unit used for describe motion?

• displacement and velocity

• frequency and wavelength

• direction and distance

• time and acceleration

Multiple Choice

The SI unit for speed is_______.

• meters per second

• miles per hour

• miles per second

• meters per hour

Multiple Choice

The SI unit for distance is_______.

• inches

• feet

• meters

• kilometers

Multiple Choice

The SI unit for time is_______.

• hours

• minutes

• seconds

• millisecond

Multiple Choice

Which quantity refers to the rate of movement, or fast a moving object is?

• displacement

• speed

• time

• force

​Distance vs Displacement

​Distance is the total length of travel irregardless of the direction of motion. It is a scalar quanitity.

Displacement is the total distance moved based on where the object came from. It is a vector quantity

​Distance vs Displacement

​Distance is the total length travelled irregardless of the direction of motion. It is a scalar quantity.

Displacement is the total distance moved based on where the object came from. It is a vector quantity. It is also defined as "change in position."

​Distance vs Displacement

​Distance is the total length travelled irregardless of the direction of motion. It is a scalar quantity.

Displacement is the total distance moved based on where the object came from. It is a vector quantity. It is also defined as "change in position."

​Distance vs Displacement

​If you walk from home going to school for 2.5 km and then went back home...

​

your distance travelled is

​5.0 km

​your displacement is​

​0 km.

​Distance vs Displacement

In solving for displacement, you can assign positive or negative directions.​

​

​If you took 3 steps forward, 5 steps backwards, and then 10 steps forwards again, what will be the displacement?

​

(+5 steps) + (-7 steps) + (+10 steps) = ​+8 steps

​

What about the total distance travelled? ​

Multiple Choice

The sum of all movements from start to the end of motion is best described as____.

• distance

• displacement

• motion

• donkey

Multiple Choice

The change in an objects position from the final position to initial position.

• displacement

• distance

• motion

• reference point

Multiple Choice

A man walks 5 miles forwards, 6 miles backwards and then 2 miles forwards. What is his displacement?

• 1 mile forward

• 13 miles

• 3 miles forward

• 1 mile

Multiple Choice

Jerry walked from home to school, then from the school to the park. What is his total distance?

• 2 km

• 5 km

• 8 km

• 10 km

Multiple Choice

A persons walks 50 meters directly north, stops, and then travels 32 meters directly south.  What is their distance traveled?

• 82 meters
• 18 meters
• 32 meters

​Speed vs Velocity

​Speed is the total distance travelled per unit of time. It refers to how fast the object moves.

Velocity is the total displacement per unit of time. It is the speed in a given direction.

​

Both are measured using the SI unit m/s or ms^-1​ or sometimes km/hr or kmhr^-1

​

​Speed vs Velocity

​Speed is the total distance travelled per unit of time. It refers to how fast the object moves.

Velocity is the total displacement per unit of time. It is the speed in a given direction.

​

Both are measured using the SI unit m/s or ms^-1​ or sometimes km/hr or kmhr^-1

​

Formula for ​Velocity and Speed

Multiple Choice

While going to school, a student walks an average of 5 km/hr west for 12 blocks.

• Speed
• Acceleration
• Velocity

Multiple Choice

While on a trip, a family travels east from San Antonio to Houston going 70 mph.

• Speed
• Acceleration
• Velocity

Multiple Choice

Speed in a given direction is the definition of ____. 

• Speed
• Velocity
• Acceleration
• Direction

Multiple Choice

A car traveling 300 miles in 5 hours is an example of _____. 

• Speed
• Velocity
• Acceleration
• Direction

Multiple Choice

A ball rolling west at 5 cm per second is an example of ____. 

• Speed
• Velocity
• Acceleration
• Direction

Multiple Choice

Distance over time is the definition of ___. 

• Speed
• Velocity
• Acceleration
• Direction

Multiple Choice

What is the formula to calculate speed?

• Speed = time/distance
• Speed = distance/time
• Speed = distance x time
• Speed = time x distance

​Average vs Instantaneous Speed

​speed for the travel, speed for a specific instance

​As an object travels, it may change speeds. It may speed up, slow down, change direction or even stop.

​

The speed for the total distance over time frame is the average speed.

​

The speed at any given instance is the instantaneous speed. ​

​Acceleration

​speeding up, slowing down, or changing directions

​When an object speeds up, slows down or changes direction, it also changes the displacement and velocity. This change is called acceleration.

​

Acceleration can be a positive or negative depending on the direction of the velocity (+ or -) and whether it speeds up or slows down.

​Acceleration

​Acceleration

​You experience acceleration when you:

• step on the gas and speed up

• step on the breaks and slow down

• turn your steering wheel​

​

​In this graph, velocity is constant, and acceleration is zero because there is no change in velocity.

​

​

​In this graph, initial velocity is 50 m/s, and final velocity is 0 m/s. Acceleration is NOT zero because the velocity changed.

​

Multiple Choice

The velocity of an object increases from 30 m / s to 50 m / s in 5.0 seconds.

What is the average acceleration of the object?

• 0.10 m / s²

• 0.25 m / s²

• 4.0 m / s²

• 10 m / s²

Multiple Choice

A car travels at an average speed of 60 km / h for 15 minutes. How far does the car travel in 15 minutes?

• 4.0 km

• 15 km

• 240 km

• 900 km

Multiple Choice

If you drive for 2 hours and travel 120 miles. What was your average speed.

• 60

• 60 mi/hr

• 240 miles

• 2 hours

Multiple Choice

You roll a tennis ball a distance of 18 meters it takes 6 seconds to cover the distance. What is the average speed of the tennis ball?

• 3 km/s

• 6 m/s

• 3

• 3 m/s

Multiple Choice

$$a=\frac{\Delta v}{t}$$  

Sami coasted on her bike straight down a hill, accelerating from a speed of 3 m/s to 15 m/s in a total time of 6 seconds. What was her acceleration?

• 1 m/s²

• -1 m/s²

• 2 m/s²

• 1m/s

Multiple Choice

the unit of acceleration is

• (m/s²)

• jouls

• m

• s

Multiple Choice

A bus starts from rest and accelerates to 14 m/s in 4 s. What is the average acceleration of the bus?

• 3.5 m/s2

• 5.9 m/s2

• 10.5 m/s2

• 24 m/s2

​Kinematic Equations

​Other equations can also be used in solving kinematic problems.

Multiple Choice

What are the standard units of acceleration?

• m

• s

• m s^-1

• m s^-2

Multiple Choice

What is the acceleration of a train that takes 2.3km to stop from a speed of 67 m/s

• 0.98 m/s²

• -0.98 m/s²

• 0.12 m/s²

• -0.12 m/s²

Multiple Choice

A space shuttle accelerates from rest (0 m/s) to a top speed of 600 km/h. if the average acceleration of the space shuttle is 10m/s, what is the distance the space shuttle accelerates over (roughly)

• 1200m

• 1390m

• 1800m

• 2,290m

Multiple Choice

An airplane lands on a runway with a velocity of 150 m/s. How far will it travel until it stops if its rate of deceleration is constant at -3 m/s²?

• 525 m
• 3750 m
• 6235 m
• 9813 m