Quantity and motions

Scalar and Vector QuantitiesScalar and Vector Quantities

Quantity

Scalar

Vector

magnitude(number). magnitude(number) and its direction

work , energy , length, density, volume, speed , distance , and time

work , energy , length, density, volume, speed , distance , and time

A car moves due west with the velocity of 50 m/s force , Rotation moment , electric current ,displacement, acceleration, weight

A car moves due west with the velocity of 50 m/s force , Rotation moment , electric current ,displacement, acceleration, weight

Scalar Quantity Unit of Scalar Quantity

Energy J , kJ , Cal

Temperature °C

Time s , min , hr

Area cm² , m² , km²

Volume cm3 , dm3

Speed m/s ,km/hr

Scalar Quantity

exercise 1.11. A wind blows from the east at 100 miles/hour……………………………………………………………………………………

2. I add 20 grams of sugar to a recipe.…………………………………………………………………………………..

3. I buy a liter (1000ml) bottle of water.……………………………………………………………………………………

4. A plane flies south at 500 miles/hour…………………………………………………………………………………..

5. A man walks 3 miles north then turns right and walks 4 miles east.…………………………………………………………………………………

6. 20 0C of water……………………………………………………………………………………

MotionMotion

1. Linear motion : a motion occurring in a straight line. It is the most basic of all motions.

2. Projectile motion : a motion occurring when an object is thrown or projected at an angle into the air

Example arrow being shot , golf balls being hit and basketball being thrown in to the net Example arrow being shot , golf balls being hit and basketball being thrown in to the net

2.3 Circular motion : a motion occurring when object moves in a circular path. The motion has a fixed radius.

Distance and Displacement

1. Distance has only magnitude (size)

2. Displacement is a vector quantity which refers to the shortest length connection the starting point and the end point.

example

1. Ann walks from the point A to B Distance =Displacement =

2. Ann walks from the point A to B to C

Distance =Displacement =

3. Ann walks from the point A to B to C to DDistance =Displacement =

4. Ann walks from the point A to B to C to D to ADistance =Displacement =

exercise 3.11. A car moved 50 m to the North. 1.1 What is its displacement?

1. A car moved 50 m to the North. 1.2 What is the displacement?

2. A car moved 20 km East and 70 km West. 2.1 What is the distance?

2.2 What is the displacement?

3. John walks from the point A to B to C.

3.1 What does the distance he travel?

3.2 What is the displacement?