A student made the table shown to list some contact and non-contact forces. Examples of Forces
Contact Forces Non-Contact Forces
The force exerted by a stretched spring The force applied by Earth and sun on each other
The electrical force exerted by a positive charge on a negative charge Magnetic attraction between two magnets

Which statement best explains why the table is incorrect?
Spring force is a force acting at a distance.
Electrical force is not a contact force.
Gravitational force can act between planets and sun only when they are in contact.
Magnetic attraction is a contact force

Unpolarized light falls on two polarizer sheets whose transmission axes are at right angles. a third polarizer is placed between the first two so that its axis makes a 52-degree angle with the axis of the first polarizer. a) what fraction of the incident light intensity is transmitted through the first polaroid? b) what fraction of the incident light intensity is transmitted through the second polaroid? c) what is the angle of polarization of the light that enters the third polaroid? d) what fraction of the incident light intensity is transmitted through the third polaroid. e) what happens if the middle polaroid is removed?

As microwave light travels through a liquid, it moves at a speed of 2.2 x 108 m/s. if the frequency of this light wave is 1.1 x 108 hz, what is the wavelength of this microwave?

When solid surfaces slide over each other the kind of friction that occurs is called friction