forces new

8/13/2019 Forces New

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Unit 3: Forces in Engineering

1. Work in group:

1. Identify forces acting on the car and airplane:

Driving force

Weight

Air resistance

Friction

Reaction force

Lift

Weight

Drag

Thrust


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2. Matching the vocabulary with its definition:

Definition Vietnamese Translation

1. magnitude2. elasticity

3. weight

4. buoyancy

5. Newton6. equilibrium

7. gravity

a. how heavy sb/sth is, which can be measured in, forexample, kilograms or pounds

b. the quality that sth has of being able to stretch and

return to its original size and shape

c. the force that attracts objects in space towards eachother, and that on the earth pulls them towards the

centre of the planet

d. a unit of force

e. a state of balance, especially between opposing

forces or influences

f. ability to float or keep things floating

3. Read the text and choose TRUE/ FALSE

1. When the ship is in equilibrium, the magnitude of B and W is different.2. Springs exert more force the more they are compressed.

3. Weight is measured in Newton.

4. Weight is the quantity of matter in an object.

5. There is no benefit from friction.


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Language study: Passive in describing process

Passive Review:

1. Lasers are usedin all sorts of settings like welding, cutting, surgery, communications, reading bar codes at the

supermarket or reading the information stored on a CD or DVD.

2. These files are convertedinto pdf.

3. The power is deliveredto every part of the system.

4. Vocabulary Enlargement: Forces in Engineering

S + BE + V- ed/ V 2


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5. Translate the following text into Vietnamese:

Frictionis the force resisting the relative motion of solid surfaces, fluid layers, and material elements sliding

against each other. There are several types of friction:

Dry frictionresists relative lateral motion of two solid surfaces in contact. Dry friction is subdividedinto static friction("stiction") between non-moving surfaces, and kinetic frictionbetween moving surfaces.

Fluid frictiondescribes the friction between layers within a viscous fluid that are moving relative to each other Lubricated frictionis a case of fluid friction where a fluid separates two solid surfaces. Skin frictionis a component of drag, the force resisting the motion of a solid body through a fluid. Internal frictionis the force resisting motion between the elements making up a solid material while it

undergoes deformation.

When surfaces in contact move relative to each other, the friction between the two surfaces converts kinetic

energy into heat. This property can have dramatic consequences, as illustrated by the use of friction created by

rubbing pieces of wood together to start a fire. Kinetic energy is converted to heat whenever motion with friction

occurs, for example when a viscous fluid is stirred. Another important consequence of many types of friction can

be wear, which may lead to performance degradation and/or damage to components. Friction is a component of the

science of tribology.

Friction is not itself a fundamental force but arises from fundamental electromagnetic forces between the charged

particles constituting the two contacting surfaces. The complexity of these interactions makes the calculation of

friction from first principles impossible and necessitates the use of empirical methods for analysis and the

development of theory.

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