dynamic engineering system - linear motion notes

8/3/2019 Dynamic Engineering System - Linear Motion Notes

1/22


2/22

tulisnota.blogspot.com

Linear MotionMotion with constant acceleration


3/22


Velocity

Time

u

u = initial velocity

v

v = final velocityGradient

gradient = acceleration

acceleration = a

v u

Rearrange equation:

t

1


4/22


Velocity

Time

u

u = initial velocity

v

v = final velocity

v u

Rearrange equation:

t

area

under = distance

graph

distance = s

Area 1

area

under = area 1 + area 2

graph

Area 2


5/22


We have:

We also have:

So,

Rearrange equation:

2


6/22


We have:

We also have:

So,

Rearrange equation:

3


7/22


3 Main Equations:

}


8/22


Alternative method

}


9/22


Alternative method

}


10/22


Example 1 - Question

}


11/22


Example 2 -Question

} Find the deceleration of a car that isbrought to rest in 60 m from a speed of 45

km/h. What is the time taken?

} t = 9.6 s #


12/22



}


13/22



}


14/22


Example 4 - Solution

} s = 133.3 m. The car hit the cow becausewith the given retardation, the car will

stop after 133.3 m #

} v = 16 m/s. The car hit the cow becauseafter 50 m, the car still have velocity, thatmeans the car is still moving #


15/22



}


16/22


Revision

}


17/22


Revision

}


18/22


Linear MotionVertical motion under gravity


19/22


Acceleration due gravity = g

If an object moves


20/22



}An object is projected vertically upwardswith an initial velocity of 40 m/s. Calculate

(a) the maximum height reached, (b) thetime taken to reach the maximum height,(c) the time taken for the object to fallback to its initial point of projection.

} s = 81.5 m #

} t = 4.1 s #

} t = 4.1 s #


21/22


Revision

}A brick falls off the top of building. If theheight of the building is 20 m, determine

the time the bricks takes to reach theground.

}A ball is thrown vertically upwards with avelocity of 15 m/s. Determine the greatest

height reached above the point ofprojection.


22/22


Revision

}A ball is thrown vertically downwards withan initial velocity with an initial velocity of

4 m/s from the edge of a cliff. If the ballhits the ground at the base of the cliffafter 2s, determine the height of the cliff.

dynamic engineering system - linear motion notes

Documents