Both physical quantities have a unit of length, which is m in SI system.

Distance is a scalar quantity , whereas displacement is a vector quantity.

Define : Distance ………………………………………………………….

Define : Displacement

………………………………………………………....

Is the distance an object travels divided by the time it takes to travel that distance.

d

S t

Unit of speed = unit of distance/unit of time

Any unit of distance divided by unit of time is a unit of speed.

Examples are :…………………………

Unit of speed in SI system:………………..

Graphs are the easiest tool to derive data. You can describe the motion of an object using

graphs.

d d

t

If the speedometer on your car reads a constant 50 kilometers per hour. How far will you go in 15 minutes?

An average person can walk 1 kilometer in 10 minutes.

a. What is the speed in miles per hour? In kilometers per hour?

b. How long would it take an average person to walk 3.5 miles? To walk 10 km?

c. How far can an average person walk in 45 minutes? In 1.5 hours?

It has the same numerical value as speed, but it is a vector quantity.

It has the same units as speed

meters per second

Feet per second

Miles per hour

Average velocity is the total distance traveled divided by the total time of travel.

Instantaneous velocity is the velocity at a specific time . It is the reading of the car’s speedometer .

Wendy walks 10 m in one direction at 2 m/s, then runs 6 m in the same direction at 6 m/s. Next, she stops for 4 seconds, and finally walks in the opposite direction at 4 m/s for 6 seconds.

Wendy’s average speed is closest to: 1. 1 2 m s 2. 1 m s 3. 1 1 2 m s 4. 2 m s 5. 2 1 2 m s 6. 3 m s 7. 3 1 2 m s 8. 4 m s 9. the negative of one of the choices above 10. impossible to determine

.QuestionMichael is going to the store 6 miles away. He rides his bike at 12 mph for the first half of the trip, then walks at 4 mph for the remainder.Michael’s average speed for the trip to the store is closest to:1. 2 mph2. 4 mph3. 6 mph4. 8 mph5. 10 mph6. 12 mph7. 14 mph8. Exactly halfway between two of the values above9. Impossible to determine

Is defined as a change in velocity divided by the time it takes for that change to occur.

.

a= 10 mi/hr/s

t=0s 1s 2s 3s 4s

V=0 mi/hr10 20 30 40

When an object is accelerated in a uniform way from a standing start, the distance it covers in a given time depends on the square of the time.

The instantaneous velocity of a uniformly accelerating object that started at rest equals the acceleration multiplied by the total time of acceleration.

A sprinter accelerates from the starting blocks to a speed of 11 meters per second in 1.5 seconds.

a) What is his acceleration?

b) How far does the sprinter travel during the acceleration?

c) How fast is the sprinter going when he’s halfway through the period of acceleration?

d) How far has the sprinter traveled in the first 0.75 seconds?

f) Assuming the sprinter covers the remaining 91.8 meters at a constant speed of 11m/s, what will be his time for that event?

All objects moving under the influence of gravity only are said to be in free fall◦ Free fall does not depend on the object’s original

motion

All objects falling near the earth’s surface fall with a constant acceleration

The acceleration is called the acceleration due to gravity, and indicated by g

g= 9.8 m/s2 = 32 feet/s2

A ball is thrown straight up into the air. Its position at 7 instants of time are shown in the figure;

the maximum height is reached at position 4. At which of the labeled points is the acceleration

of the ball smallest? 1. point 1 2. point 2 3. point 3 4. point 4 5. point 5 6. point 6 7. point 7 8. Exactly 2 of the points shown 9. More than 2 of the points shown 10. Impossible to determine

Use the same equations of constant acceleration Motion , a= -g=-9.8 m/s2

The tallest building in the United States is the Sears Tower in Chicago, with a height of 443 m. Ignoring air resistance , how fast would a penny dropped from the top be moving when it hit the ground?

A baseball is released at rest from the top of the Washington Monument. It hits the ground after falling for 6.0 s. What was the height from which the ball was dropped? (assume air resistance is negligible)

Suppose you throw a ball straight up into the air with an initial speed of 25 m/s :

a) How high will it go?

b) How long will it take to return to the ground?

The Law of Compound Motion:

Motion in one dimension has no effect on motion in another dimension.

http://phet.colorado.edu/sims/projectile-motion/projectile-motion_en.html

If you stand on a high cliff and throw a rock outward.

Two Motions:

1. Horizontal Motion : Constant velocity Motion.

2. Vertical Motion : Constant acceleration Motion (a=-g=-9.8 m/s2)

The path of the motion is Parabola.

Motion Horizontal Motion Vertical Motion

Force No Force Gravity

Acceleration No Acceleration Acceleration due gravitya=-g=-9.8 m/s2

Velocity Constant Changing at a rate of 9.8 m/s every second.

Equations

tvd t

vva 0

2

02

1attvd

Suppose a person emerges from the cannon’s mouth with a vertical velocity of 20 m/s and a horizontal velocity of 8 m/s .

How long will it take to get to the top of the arc?

How far away would you have to place the net to make sure the landed safely?

A baseball is hit off the edge of a cliff horizontally at a speed of 30 m/s. It takes the ball 3 seconds to reach the ground, with no air resistance.

a) How far from the cliff wall does the ball land?

b) How high is the cliff wall?

The acceleration of an object moving in a circle is equal to the square of its speed divided by the radius of the circle.

The acceleration’s direction is towards the center.

R

vac

2