7 rectilinear motion

RECTILINEAR

MOTION

MOTION

is the continuous change in

the position or location of an

object

TYPES OF MOTION

1. Curvilinear Motion

2. Rotational Motion

3. Vibratory Motion

4. Rectilinear Motion

Rectilinear Motion

is motion along a straight line

QUANTITIES OF MOTIONSpeed

a scalar quantity which is the ratio of

distance,d over elapsed time, t

units: m/s , cm/s , ft/s

Velocity, v

a vector quantity which is the ratio

of displacement,s over elapsed time, t

a speed with direction

units: m/s , cm/s , ft/s

Acceleration, a

a vector quantity which is the

measure of the change of velocity per

unit time

units: m/s2 , cm/s2, ft/s2

KINDS OF RECTILINEAR MOTION

1. Constant Motion

*or constant velocity (no acceleration)

*object traverses the same

displacement per unit time interval

2. Uniformly Accelerated Motion

*constant acceleration

*the object is moving with constant

acceleration

3. Variably Accelerated Motion

*acceleration is not constant

EQUATIONS FOR UNIFORMLY

ACCELERATED MOTION

EXERCISES

1. During a time interval of 5 hours, a

car travels toward the north a

distance of 350km. Find the average

velocity of the car.

2. The velocity of a train changes from

30km/h to 60km/h in 11 seconds.

Find its acceleration in m/s2.

3. Starting from rest, a truck acquires a

velocity of 20km/h during a time of 15

seconds. What is its acceleration in

m/s2?

4. The brakes of an automobile travelling

with a velocity of 20m/s are suddenly

applied. If the automobile comes to a

stop after 5 seconds, what is its

acceleration?

5. A bicycle starting from rest is

accelerated 5m/s2. How far will it

travel after 10 seconds?

6. A train changes its velocity from 30m/s

to 80m/s while travelling a distance of

140m. Find its acceleration. Find the

time it needs to change in velocity.

FREE - FALL

Motion of a Free-Falling Objects

is a special case of uniformly

accelerated rectilinear motion

g – the acceleration due to gravity or

gravitational acceleration

* 9.8 m/s2

*980 cm/s2

*32 ft/s2

EXERCISES

1. A ball is dropped from rest at a

height of 50 m above the ground.

What is the speed just before it hits

the ground? How long does it take to

reach the ground?

2. A stone is thrown vertically up. It

reaches a maximum height of 19.6

m. What is its initial velocity? After

how many seconds will it return to

the ground?

3. A ball is thrown vertically up and

returns to the ground after 6

seconds. With what velocity was it

thrown? How high did the ball go?