Intro to Electric Forces

Physics 12

Unit Circle

Using the Unit Circle with Vector Components

x

y

A

Ax=Acosθ (positive)

θ

Ay=Asinθ (positive)

Practice Problems1) 4.5m/s, 27°2) 73N, 73°3) 42m, 48°

Solutions1) vx=4.0m/s, vy=2.0m/s2) Fx=21N, Fy=70N3) dx=28m, dy=31m

Using the Unit Circle with Vector Components

x

y

A

Ax=Acosθ (negative)

θAy=Asinθ (positive)

Practice Problems1) 7.3m/s, 132°2) 3.8N, 114°3) 18m, 164°

Solutions1) vx=-4.9m/s, vy=5.4m/s2) Fx=-1.5N, Fy=3.5N3) dx=-17m, dy=5.0m

Using the Unit Circle with Vector Components

x

y

A

Ax=Acosθ (negative)θ

Ay=Asinθ (negative)

Practice Problems1) 62m/s, 192°2) 112N, 256°3) 23m, 235°

Solutions1) vx=-61m/s, vy=-13m/s2) Fx=-27.1N, Fy=-109N3) dx=-13m, dy=-19m

Using the Unit Circle with Vector Components

x

y

A

Ax=Acosθ (positive)θ

Ay=Asinθ (negative)

Practice Problems1) 41m/s, 303°2) 2.6N, 294°3) 8.4m, 338°

Solutions1) vx=22m/s, vy=-34m/s2) Fx=1.1N, Fy=-2.4N3) dx=7.8m, dy=-3.1m

Angle Conversions W37°S W48°N S21°W S34°E E17°S E42°N N73°E N27°W

217° 132° 249° 304° 343° 42° 17° 117°

Electroscope

Draw a diagram showing the forces that exist on the leaves of the electroscope when it is placed close to the Van de Graff generator

Pith Ball

Draw a free body diagram of the pith ball when it is brought close to the Van de Graff generator

Do we have the skills to address this situation?