Science Exam 9th Grade Semester 1

Reaction time

The time it takes to respond to a situation

Random errors

Errors that cannot be corrected by calculator

Systematic errors

Errors that can be corrected by calculation

Accuracy

How close a series of measurements are to an accepted value

Precision

How close a series of measurements are to each other

Speed

The distance traveled per unit time

Constant speed

Speed that does not change over a period of time

Average speed

The total distance traveled divided by the time it took to travel that distance

Instantaneous speed

The speed at a given moment

Velocity

Speed in a given direction

Doppler effect

The change in the pitch or frequency of a sound for an observer that is moving relative to the source of the sound

Reaction distance

The distance that a vehicle travels in the time it takes the driver to react

Initial speed

The speed at which you begin to apply the brakes

Breaking distance

The distance required to bring the vehicle to rest once the breaks are applied.

Stopping distance

Minimum distance required to stop a vehicle in an emergency

Acceleration

The change in velocity with respect to a change in time

Vector

A quantity that has both magnitude and direction

Negative acceleration

A decrease in velocity with respect to time

Positive acceleration

An increase in velocity with respect to time.

Force

An interaction between two objects that can result in an acceleration of either or both objects.

Pressure

Force that is spread out over a given area

Kinetic Energy

The energy possessed by a moving body

Law of conservation of momentum

The momentum before a collision is equal to the momentum after a collision

Newton's third law of motion

If object A and object B collide, the force of object A and B will be equal and opposite to the force of object B on A.

Newton's First Law

An object in motion will stay in motion at a constant speed and travel in a strait line unless a force acts on it.

Newton's Second Law

If a body is acted on by an unbalanced force it will accelerate in the direction of the unbalanced force. (The smaller the mass, the bigger the acceleration.)

Inertia

The natural tendency of an object to remain at rest or to remain moving with constant speed in a straight line.

First collision

Vehicle hits an object and comes to a stop or slows down.

Second collision

People in the vehicle will continue to move at the same speed until they are stopped by the interior parts of the vehicle.

Third collision

The brain and body organs are also moving at the speed and will continue to move until the shell of the body is stops them.

Work

The amount of force applied on an object over a certain distance

Does work equal the change in kinetic Energy? True/False

True

Whiplash

The common name for a type of neck injury to muscles of the neck

What is the unit of work?

Joule

What is the unit of pressure?

Pascals

What is the unit for kinetic energy?

Joule

What is the unit for momentum?

kg\*m/s

What is momentum?

The product of the mass and the velocity of an object; momentum is a vector quantity

What is impulse?

A change in momentum of an object

What is the unit of force?

Newtons

What is unbalanced force?

It is the force applied in one direction is greater than the force applied in the opposite direction.

What is a overlap zone?

It is where the GO zone and STOP zone overlap, and the driver has a choice to either stop or go safely.

What is the Dilemma Zone?

It is where there is a gap between the GO zone and STOP zone.

Does a good intersection have a Overlap Zone or Dilemma Zone?

Overlap Zone

What is the STOP zone?

It is all positions where the automobile can safely stop before reaching the intersection

The width and the yellow-light time has effect in the STOP zone? True or False

False

What is the GO zone?

It is all positions where the automobile can safely make it through the intersection when the light turns yellow.

Breaking (negative) acceleration and the driver’s reaction time have no effect in the GO zone?

True

What is the SI unit of length?

Meter

What is the SI unit of mass?

Kilogram

What is the SI unit of time?

Second

What is the SI unit of temperature?

Kelvin

What is the SI unit of current?

Ampere

Work only increases kinetic Energy. True or False

False

If you double your velocity, your kinetic energy is quadrupled? True or False

True

The greater the stopping distance, the greater the force applied over the distance. True or False

False

Momentum is a vector quantity. True or False

True

It is possible for an object to lose inertia. True or False

True

An objects mass does not affect its inertia. True or False

False

The speed of the car has a effect on the reaction time of a person driving the car. True or False

False

Two equal-mass safety dummies are being used to test seat belts. Dummy A has a wide seat belt and Dummy B has a narrow seat belt. Both dummies are crashed into a barrier while in the same car. Which statement below best describes the forces needed to stop each dummy?

Dummy B’s force is bigger than Dummy A’s

Whiplash is most prominent in which type of collison?

Rear-end collisions

A constant net force of 20 N acts on an object of mass 5 kg. As the mass of the object is increased, the acceleration of the object will do what?

Decrease

F=ma is in what law of Newton?

Newton’s second law of motion