Force and Motion

Draw a picture explaining the scientific difference between pushing and pulling.

Explain the science of heat from friction, such as when you rub your hands together.

Using appropriate vocabulary words, write a scientific description of the forces at work when a T-ball is hit from its T. Include all scientific details that take place in the force and motion of the bat, the ball and any effects of this event.

Using a force meter (spring scale), measure how much force is needed to move a book five inches across a smooth table. Experiment with other classroom items. Take a look at these instructions using a mug as an example.

Predict how long it will take a ball to roll a measured distance over a variety of surfaces. Roll the ball several times over the surfaces and chart the time. Suggested surfaces: blacktop, gym floor, grass, sandbox, carpet, etc. Note the effect of friction in the experiment.

Place a string through a straw. Inflate a balloon and estimate its volume using centimeter cubes. Tape the straw to the side of an inflated balloon. Measure how far the balloon will travel when the opening of the balloon is released and the air is allowed to escape. Make changes to the volume of air in the balloon, estimate the volume again and chart the distance.

• A situation that people want to change or create can be approached as a problem to be solved through engineering. Such problems may have many acceptable solutions.

• Examples of problems requiring a solution could include having a marble or other object move a certain distance, follow a particular path, and knock down other objects. Examples of solutions could include tools such as a ramp to increase the speed of the object and a structure that would cause an object such as a marble or ball to turn.

• Pushes and pulls can have different strengths and directions.

• Pushing or pulling on an object can change the speed or direction of its motion and can start or stop it.

• When objects touch or collide, they push on one another and can change motion.

• A bigger push or pull makes things speed up or slow down more quickly.

• Examples of pushes or pulls could include a string attached to an object being pulled, a person pushing an object, a person stopping a rolling ball, and two objects colliding and pushing on each other.

Examples of problems could include constructing a latch to keep a door shut and creating a device to keep two moving objects from touching each other.

An example of static electricity force could include the force on hair from an electrically charged balloon and the electrical force on hair from an electrically charged balloon.. Examples of a magnetic force could include the force between two permanent magnets, the force between an electromagnet and steel paper clips, and the force exerted by one magnet versus the force exerted by two magnets. Examples of cause and effect relationships could include how the distance between objects affects strength of the force and how the orientation of magnets affects the direction of the magnetic force.

• Force applied to an object can alter the position and motion of that object: revolve, rotate, float, sink, fall, and at rest.

• The patterns of an object's motion in various situations can be observed and measured; when that past motion exhibits a regular pattern, future motion can be predicted from it.

• Examples of motion with a predictable pattern could include a child swinging in a swing, a ball rolling back and forth in a bowl, and two children on a see-saw.

• Each force acts on one particular object and has both strength and a direction. An object at rest typically has multiple forces acting on it, but they add to give zero net force on the object. Forces that do not sum to zero can cause changes in the object's speed or direction of motion.

• Examples could include an unbalanced force on one side of a ball can make it start moving, and balanced forces pushing on a box from both sides will not produce any motion at all.

When objects collide, the contact forces transfer energy so as to change the object’s motion.

The faster a given object is moving, the more energy it possesses.

• The gravitational force of Earth acting on an object near Earth's surface pulls that object toward the planet's center.

• "Downward" is a local description of the direction that points toward the center of the spherical Earth.

• Motion energy is properly called kinetic energy; it is proportional to the mass of the moving object and grows with the square of its speed.

• Emphasis is on descriptive relationships between kinetic energy and mass separately from kinetic energy and speed. Examples could include riding a bicycle at different speeds, rolling different sizes of rocks downhill, and getting hit by a wiffle ball versus a tennis ball.

• Forces that act at a distance (electric, magnetic, and gravitational) can be explained by fields that extend through space and can be mapped by their effect on a test object (a charged object, or a ball, respectively).

• Examples of this phenomenon could include the interactions of magnets, electrically-charged strips of tape, and electrically-charged pith balls. Examples of investigations could include first-hand experiences or simulations.

• Gravitational forces are always attractive. There is a gravitational force between any two masses, but it is very small except when one or both of the objects have large mass-e.g., Earth and the sun.

• Examples of evidence for arguments could include data generated from simulations or digital tools; and charts displaying mass, strength of interaction, distance from the Sun, and orbital periods of objects within the solar system.

• Electric and magnetic (electromagnetic) forces can be attractive or repulsive, and their sizes depend on the magnitudes of the charges, currents, or magnetic strengths involved and on the distances between the interacting object.

• Examples of devices that use electric and magnetic forces could include electromagnets, electric motors, or generators. Examples of data could include the effect of the number of turns of wire on the strength of an electromagnet, or the effect of increasing the number or strength of magnets on the speed of an electric motor.

• The motion of an object is determined by the sum of the forces acting on it; if the total force on the object is not zero, its motion will change. The greater the mass of the object, the greater the force needed to achieve the same change in motion. For any given object, a larger force causes a larger change in motion.

• All positions of objects and the directions of forces and motions must be described in an arbitrarily chosen reference frame and arbitrarily chosen units of size.

• Emphasis is on balanced (Newton's First Law) and unbalanced forces in a system, qualitative comparisons of forces, mass and changes in motion (Newton's Second Law), frame of reference, and specification of units.

• For any pair of interacting objects, the force exerted by the first object on the second object is equal in strength to the force that the second object exerts on the first, but in the opposite direction (Newton's third law).

• Examples of practical problems could include the impact of collisions between two cars, between a car and stationary objects, and between a meteor and a space vehicle.