UNIT REVIEW ? FORCE + MOTION

Question 1

What is gravity?

Answer 1

Gravity is a force that causes matter to be attracted to other matter. Gravity is a relatively weak force compared to other forces, such as electricity and magnetism. The larger the mass of an object, the greater its gravitational pull on another object.

Question 2

How does the force of gravity affect objects on earth and in our Solar System?

Answer 2

The force of gravity acting on an object on Earth determines the weight of the object. Earth’s gravity pulls masses near its surface towards the center of the Earth. The gravity of the sun causes the Earth and other planets to orbit around it. The farther away two objects are from each other, the weaker the force of gravity between them.

Question 3

What happens when two unbalanced forces act on an object?

Answer 3

If two unbalanced forces act on an object in opposite directions, the object will move in the direction that the stronger force is acting. If two forces act in the same direction on an object, the forces add together and the object experiences a greater force in that direction.

Question 4

What kind of forces act on an object?

Answer 4

Some forces are contact forces, and some forces can act from a distance. Contact forces are forces that occur when two masses are directly touching, such as the force of friction. Forces that can act from a distance are the electrical force, magnetic force, and gravitational force.

Question 5

What is motion?

Answer 5

motion is a change in position over time

Question 6

What causes an object to speed up or slow down?

Answer 6

Unbalanced forces acting on an object can change the object’s speed, causing it to speed up or slow down.

Question 7

How can we describe the motion of an object?

Answer 7

The motion of an object can only be described relative to the observer or to other objects. This is called A FRAME OF REFERENCE. The motion of an object may appear different from different frames of reference. For example, people on a train may not appear to move compared to one another. However, compared to people walking on the street, the people in the train are traveling quickly.

Question 8

What is friction?

Answer 8

Friction is the contact force between two solids, liquids, or gases that slide past one another. Friction always resists the motion of objects.

Question 9

How does friction affect the motion of an object?

Answer 9

Friction is a force that acts in the direction opposite of an object’s motion. When there is friction, the energy of an object’s motion is converted into heat energy. If no outside forces are applied to keep an object in motion, friction will always cause an object to lose its energy of motion and come to a stop.

Question 10

What is kinetic energy?

Answer 10

Kinetic energy is the energy of moving things.

Question 11

What are some examples of kinetic energy?

Answer 11

A rolling ball, a swinging rope, a vibrating spring, small particles moving in matter (such as particles in air or water)

Question 12

What are some examples of kinetic energy being transformed into potential energy?

Answer 12

Kinetic energy transforms into potential energy when an object moves uphill, when an elastic object such as a spring stretches out to its longest position, or when a pendulum swings up to its highest point.

Question 13

What is the relationship between net force applied, mass, and change in motion of an object?

Answer 13

When a net force is applied to an object that has mass, the object will accelerate in the direction of the net force. If the forces acting on the object are balanced, there will be no acceleration.

Question 14

What is potential energy and what are some examples of it?

Answer 14

Potential energy is energy that is stored in an object and can be released at a later time. Examples of potential energy include the energy in a book resting on a table above the ground, a stretched rubber band, and a battery.

Question 15

What are 2 types of potential energy?

Answer 15

Gravitational potential energy, chemical potential energy

Question 16

What is the difference between potential energy and kinetic energy?

Answer 16

Potential energy is stored energy while kinetic energy is the energy of motion.

Question 17

How does potential energy turn into kinetic energy?

Answer 17

Sometimes energy changes from one form to another. A book resting on a table has potential energy. If it is moved to the edge of the table, it will fall to the ground. As it falls the potential energy changes into kinetic energy, which is the energy of motion.

Question 18

What is heat and what is temperature, and what is the difference between them?

Answer 18

Heat is energy that is transferred from a warmer object to a cooler object. Temperature is a measure of the average kinetic energy of the particles that make up an object. Heat is energy in transit, whereas temperature is a quantitative measure of the average translational kinetic energy of the molecules of a substance.

Question 19

What is the particle model of matter and how does it explain the changes of state that occur with variations in temperature or pressure?

Answer 19

The particle model of matter states that all matter is made of tiny particles that are in constant motion, have empty spaces between them and interact with each other. When the temperature of the particles of a solid increases sufficiently, the particles are able to move around and past each other while still maintaining close proximity with each other; this describes a liquid. As the temperature continues to increase, the particles move so fast that they are no longer bound to one another, and are free to move around the container and the space between the particles is relatively large; this describes a gas. Increasing the pressure of a gas can force the moving particles closer together, forming a liquid. At extremely high pressures, the liquid can even change into a solid.

Question 20

How can energy be released or stored by chemical means?

Answer 20

Chemical energy is energy that is stored in the bonds of chemical compounds. When these bonds are broken during a chemical reaction, energy is absorbed from the surroundings; energy is stored in the chemical bonds. When new bonds are formed, energy is released to the surroundings, often as heat.

Question 21

How is thermal energy transferred?

Answer 21

Heat can be transferred from one object to another by radiation, conduction, or convection.

Question 22

13. What is the process for developing potential design solutions?

Answer 22

This process often begins with the open-ended goal of brainstorming ideas. From there, it moves to the generation of possible solutions that, by necessity, involve constraints and criteria. Modeling plays a crucial role in this process; the models can take numerous forms.

Question 23

A newton is:

Answer 23

a measurement of unit of force; Force required to move 1 kilogram
N= 1kg x m/s2 (1 kilogram times meter per second squared)
Joule - the measurement of heat and thermal energy
Unit of energy;

1 joule = 1 newton

An object is moving at a constant speed, and a force pushes it in the same direction, the object will do what?
ACCELERATE
16 net weight