Chapter 10 Linear Motion

1.

EE007-4-0 Mechanics For Engineers
Topic 10 : Linear Motion
EE007-4-0 Mechanics For Engineers
Linear Motion
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2. TOPIC LEARNING OUTCOMES

At the end of this topic, you should be able to:
1. Differentiate position, displacement and distance.
2. Use differentiation or integration to obtain equations for position, velocity and
acceleration and subsequently solve the questions
3. Solve problems on motion with constant acceleration by using kinematics
equations
EE007-4-0 Mechanics For Engineers
Linear Motion
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3. Contents & Structure

Contents & Structure
• Rectilinear Motion – constant acceleration and variable acceleration
EE007-4-0 Mechanics For Engineers
Linear Motion
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4. Recap From Last Lesson

• Dry Friction
EE007-4-0 Mechanics For Engineers
Linear Motion
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5. DYNAMICS

Teaching Contents
DYNAMICS
• Dynamics is part of mechanics that deals with the analysis of
bodies in motion.
• Dynamics include:
a) Kinematics
Is used to relate displacement, velocity, acceleration and time without relation to the
cause of motion.
b) Kinetics
Study of the relation existing between the forces acting on a body, the mass of the
body and the motion of the body.
EE007-4-0 Mechanics For Engineers
Linear Motion
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6. RECTILINEAR MOTION

A particle moving along a straight line is said to be in rectilinear motion.
Position
The coordinate corresponding to the location of the body from a reference point. Could be mentioned in the
negative (-ve) or positive direction (+ve).
5m
O
A
+5m from reference point O
+5m
B
2m O
-2m from reference point O
-2m
EE007-4-0 Mechanics For Engineers
Linear Motion
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7. RECTILINEAR MOTION

Distance
The total accumulated travel in the given time.
Displacement
The distance directly between the start and finish, no matter how far it has
travelled in distance, with a sense of direction.
Movement of object
Distance = 5+7+7+4 = 23m
5m
1
2
3
4
EE007-4-0 Mechanics For Engineers
1m
O
2m
Linear Motion
Displacement = -1m
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8. RECTILINEAR MOTION

Speed
The total distance travelled divided by the time taken.
Velocity
The total displacement travelled divided by the time taken
8m
O
6m
2s
6s
1
2
2s
3
EE007-4-0 Mechanics For Engineers
Linear Motion
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9. RECTILINEAR MOTION

If a (acceleration) is +ve (positive) → Velocity increases
→ Particle is moving faster in the positive direction
5 m/s
3 m/s
2s
→ Particle is moving slowly in the negative direction
- 5 m/s
- 3 m/s
2s
EE007-4-0 Mechanics For Engineers
Linear Motion
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10. RECTILINEAR MOTION

If a (acceleration) is –ve (negative) → Velocity decreases
→ Particle is moving slowly in the positive direction
3 m/s
5 m/s
2s
-3 m/s
-5 m/s
Deceleration
→ Particle is moving faster in the negative direction
2s
Refers to acceleration when the speed of the particle decreases, the particle is moving
more slowly.
Linear Motion
EE007-4-0 Mechanics For Engineers
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11. RECTILINEAR MOTION

Motion of Particle
1.
Uniform Rectilinear Motion
straight line motion where the acceleration, a of the particle is zero for every
value of t. The velocity, V is therefore constant.
dx/dt = V = constant, a = 0
by integrating the equation, we get the position
x = x0 + Vt
Where x0 is the initial position.
This equation may be used only if the velocity of the particle is known to be constant.
EE007-4-0 Mechanics For Engineers
Linear Motion
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12. RECTILINEAR MOTION

EE007-4-0 Mechanics For Engineers
Linear Motion
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13. RECTILINEAR MOTION

V2 = V02 + 2a(x-xo)
EE007-4-0 Mechanics For Engineers
Linear Motion
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14. Summary / Recap of Main Points

Difference between displacement and distance
Difference between speed and velocity
Differentiation and integration for Variable acceleration
Constant acceleration formulas
EE007-4-0 Mechanics For Engineers
Linear Motion
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15. What To Expect Next Week

In Class
• Angular motion
EE007-4-0 Mechanics For Engineers
Preparation for Class
• Kinematic Equations
Linear Motion
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