How does the force of friction affect the motion of objects? It causes the object to change direction.
It causes the object to create heat energy.
It causes the object to create kinetic energy.
It causes the object to slow down or stop.

Explanation:

The concepts developed in this standard include the following:

· The position of an object can be described by locating it relative to another object or the background.

· Tracing and measuring its position over time can describe an object’s motion.

· Speed describes how fast an object is moving.

· A force is any push or pull that causes an object to move, stop, or change speed or direction.

· The greater the force, the greater the change in motion will be. The more massive an object, the less effect a given force will have on the object.

· Energy may exist in two states: kinetic or potential.

· Kinetic energy is the energy of motion.

· Friction is the resistance to motion created by two objects moving against each other. Friction creates heat.

· Unless acted on by a force, objects in motion tend to stay in motion and objects at rest remain at rest. In order to meet this standard, it is expected that students should be able to:

· identify the forces that cause an object’s motion.

· describe the direction of an object’s motion: up, down, forward, backward.

· infer that objects have kinetic energy.

· design an investigation to determine the effect of friction on moving objects.

substituting a hydrogen atom with a halogen in a hydrocarbon:

- the single bond remains single. a is wrong.

- the bond with hydrogen is as strong as with a halogen. c is wrong

- a hydrocarbon is saturated if there is no double bond. we do not know that so d is wrong.

- carbon will always have four valence electrons. e is wrong.

by elimination, the correct answer is b. the boiling point of the new compound increases.