Question of the Day Rules

• You must work alone• You may NOT USE your textbook today• You have 6 minutes to complete the

QOD

Good luck!!

Question(s) of the Day

What is the difference betweenHeat and Temperature?

Heat Vs. Temperature

• Heat is a measurement of energy. The hotter an object is, the fastest the molecules inside move. Therefore, the heat of an object is the total energy of all the molecular motion inside that object.

• Temperature, on the other hand, is a measure of the average heat or thermal energy of the

molecules in a substance.

Answers.

Answer: By reducing our energy consumption, we also reduce our impact on the environment. If we reduce our fossil fuel consumption, we generate less greenhouse gas. If we reduce our hydroelectric demands, we help prevent further flooding of land to build new dams.

1) Why is it so important to reduce energy consumption?

Answers2) Give 3 examples that we can do to reduce our energy consumption in our own homes?

Answers will vary. Examples: turning off the lights when we leave a room– turning down the heating at night and when we are away from home– using energy-efficient appliances– insulating our homes better.

What are we doing Today?• Hand in any late assignments • Question(s) of the day• Chapter 3 (ST) test on Nov. 12• Tutorial on Mon, Nov. 10• Ch. 3 – EST Notes Motion & Forces• Class work questions

The effective force is the force component that alters the motion of an object. It is the

component that is parallel to the movement of the object (p. 88).

using angles and trig ratios we can solve for different sides of a triangle

The effective force is in the direction of the acceleration. If Mr. Meades applies a 35 N force at

an angle of 27o calculate the effective force.

Mr. Meades effective force?

Cos 27o = Effective Force / 35 N

Effective Force = 35N x Cos 27o

The effective force is equal to 31.2N

What is the vertical component of the 35N force?

Sin 27 = Vertical Force/35N

Vertical Force is equal to 15.9 N

Find the combined weight of the sled and the girl if the combined mass is 30kg?

Weight = F = m x g

Weight = (30kg) x (9.8m/s2)

Weight = 294 N

Why doesn’t the sled lift off the ground?

Because

294N > 15.9 N (the vertical component)

A person is pulling a box along the floor with a force of 25 N at an angle of 65° to the horizontal. What is the effective force?

Cos 65 = effective F / 25 N

Force Effective = 10.57 N

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What is work?

• In science, the word work has a different meaning than you may be familiar with.

• The scientific definition of work is: using a force to move an object a distance (when both the force and the motion of the object are in the same direction.) p.90

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Work or Not?

• According to the scientific definition, what is work and what is not?– a teacher lecturing

to her class– a mouse pushing a

piece of cheese with its nose across the floor

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Work or Not?

• According to the scientific definition, what is work and what is not?– a teacher lecturing

to her class– a mouse pushing a

piece of cheese with its nose across the floor

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19

What’s work?• A scientist delivers a speech to an

audience of his peers. • A body builder lifts 350 pounds

above his head. • A mother carries her baby from room

to room. • A father pushes a baby in a carriage.

• A woman carries a 20 kg grocery bag to her car?

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What’s work?• A scientist delivers a speech to an

audience of his peers. No• A body builder lifts 350 pounds

above his head. Yes• A mother carries her baby from room

to room. No• A father pushes a baby in a carriage. Yes

• A woman carries a 20 km grocery bag to her car? No

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Formula for work

Work = Force x Distance

• The unit of force is newtons• The unit of distance is meters• The unit of work is newton-meters• One newton-meter is equal to one joule• So, the unit of work is a joule

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W=FD

Work = Force x Distance

Calculate: If a man pushes a concrete block 10 meters with a force of 20 N, how much work has he done?

23

W=FD

Work = Force x Distance

Calculate: If a man pushes a concrete block 10 meters with a force of 20 N, how much work has he done? 200 joules(W = 20N x 10m)

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2. How much work will it take to move a 10 kg mass at an acceleration of 2 m/s/s a distance of 10 meters in 5 seconds? This problem requires you to use the formulas for force and work.

Force=Mass x Acceleration

Work=Force x Distance

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2. How much power will it take to move a 10 kg mass at an acceleration of 2 m/s/s a distance of 10 meters in 5 seconds? This problem requires you to use the formulas for force, work, and power all in the correct order.

Force=Mass x Acceleration Force=10 x 2Force=20 N

Work=Force x DistanceWork = 20 x 10

Work = 200 Joules

Class Work Questions

From your textbookp. 101-102

Numbers: 25, 26, 27, 28