Force, mass, and movement

Contents Overview

Introduction
Activities
Expansion activities
- Ball runs & coasters
- Structures and bridges
K'Nex® vehicle album

Introduction

This page includes activities related to force, mass, and movement.

Subtopics include: energy, conservation of energy, potential energy, kinetic energy motion, speed, slope, mass, height, gravity, friction, and Newton's Laws.

Activities

Related Units

Motion - Motion unit: Spinners: tops, zoomers, twirlers, rollers: wheels, wheels & axles, cups, & spheres unit with plans & activities
Gravity friction & motion - Motion: force, gravity, acceleration, inertia, friction, & energy unit plans & activities
Relative position & motion - unit plans & activities
Investigation directory
Helmet safety and testing - mostly related to football - create challenges to test different kinds of containers (helmets) for eggs in an egg drop.

Exploration of force

Challenge

Can you move your hands toward each other so one hand feels a small push and the other a strong push?

When they are brought together fast, there is a clap. And when we clap, each hand feels the same force.
Which force is strongest? They are the same. Equal strength in the opposite direction.
What direction is each hand pushing? left right & right left. Each in the opposite direction of their motion
When is this the same? When any two objects collide.
Know as? Newton's third law of motion
Which happens first? neither. They happen at the same time. One does not cause the other.
Consider two magnets. They can attract or repel. They happen together at the same time. One is not causing the other. Their interaction causes the force and maybe motion.
When two forces interact one is not causing the other. Both forces have the same cause: their interaction.
Consider how gravity pulls objects. Each object pulls on the other. Neither one pulls on the other. They pull on each other. A basketball falling to the ground results in gravity pulling on the ball and gravity pulling on the Earth with the same force.

Summary

Whenever one object exerts a force on another object, the second object exerts an oppositely directed force of equal magnitude on the first object.

Forces always come in pairs.
They always act in opposite directions,
They happen at the same time.
They act with equal magnitude on each object in the interaction.
Forces in these paired interactions are always the same types of forces.

Assess by asking to explain the forces

Between two hands pulling on a rubber band. Rubber band pulls equally on both hands in the opposite direction it is being stretched.
Forces on a blown up balloon. Balanced air pressure inside pushing out and outside pressure pushing in.
Forces on a filled balloon with the air escaping. On a filled balloon the air pressure inside pushes outward in all directions. When released the unbalanced forces push the balloon around the room. They are unbalanced, because the force, where there is now a hole, has no outside pressure to hold it in so the air just leaves. Therefore, there is a force pushing up on the balloon but none pushing down, because there is a a hole there. The result is more air pressure pushing up on the balloon than air pressure pushes down with the resulting motion up.

Ramps, incline planes, & down hill runs

Will it get up the hill?

Challenge

The learners were challenged to collect data to show a relationship between the release height or a vehicle or ball and the height to which the ball or vehicle will climb up the other side of the valley or U shaped run.

Materials

K'Nex downhill run - double Set of K'Nex x-treme Downhill Thrill Play Set #12026. While the set is no longer available new, most of the parts are available from other sets, except the red ramps.
- See K'Nex for instruction sets
K'Nex® vehicle album
- Washers to use as weights or masses.

U shaped track set up — Double downhill set connected

Suggestions:

Consider only vertical distance when making the measurements
Measure to the nearest centimeter
Decide on test run heights: select three - 10 cm, 20 cm, 30 cm, 40 cm, 50 cm, 60 cm
Record: release height
Record: climb height
Review the data
Graph the data
Make a rule for how high a ball needs to be released to make it over a hill that is a certain height.
Explain why or how your rule works.

Will it make the turn?

Challenge learners to collect data to show the relationship between the kind of turn and the speed of the ball.

Create three kinds of turns with a track.
Can measure the diameter: 10 cm, 20 cm 30 cm and the angle of the turn 30 degrees, 45, degrees, 90 degrees, 180 degrees ...
Insert each corner and release the ball from three heights: 10 cm, 30 cm, 50 cm
Repeat with each of the other corners.
Record the data: type of corner, height, results
Review the data
Chart the data
What is the difference in the corners A, B, and C?
Make a rule for safe corners on coasters or ball runs.

How fast is fast?

Challenge learners to collect data to determine the speed of a ball or vehicle as it moves across a smooth surface or track.

Release a vehicle or ball from a point marked on a ramp
Determine how to releases it so it rolls approximately the same speed each time
Determine three distances and place markers: 100 cm 200 cm 300 cm
Find the time that it takes the vehicle or ball to reach each of the distance markers.
Do two or three time measurements for each distance.
Record the data: time to reach each distance marker.
Average the times and calculate the average speed in cm/s
Was the ball’s speed constant? Explain.
Use your data to determine a pattern to predict the speed of the ball at different distances or started higher up the ramp.
Justify your answer.

Down Hill Crash and slide investigations

Focus questions
Procedure
Photo album
Sets of data and graphs

Focus Questions

How far can the car push a bale of different weights?
Can the car crash into a bale and not move the bale?
What is the least amount that the bale will move?
How does adding weight (washers) to the bale change the distance it will slide when it is hit by the car?
How does changing the angle change how far it will slide?
How doe adding weight to the car change the distance the bale will slide?

Note:

I starteed with a U shaped track to focus on the idea that the cars lost energy when the car wouldn't go all the way up the other side. This led to a conversation about conservation of enery and what happens to the motion energy if it is conserved.

When learners explored having the car go down the track and collide, they wanted to take the U track apart to let the crash happen on the flat tile floor. When they did, the vehicle or ball would run off the end of the track, onto the floor, crash, push the slider across the floor and crash into the wall. When light weights were added, they too would slide across the floor and hit the wall.

Therefore, we decided to reassemble the u shaped track and let the slider slide up the hill.

Set up a U shaped track.

Procedure

The K'Nex® DownHill Thrill layout was used (pictures in album below) and K'Nex® vehicle album. The end of one of the plastic bales was cut off so that washers could be put inside. The bale was placed at the of the first dip. The first runs pushed the bale up the jump and across the tile floor. Later runs didn't.

Modified the plastic hay bale (cut the topoff so we could insert washers) and placed it at the bottom of the hill at the point where two tracks met.
Placed a ruler beside the track to measure the distance the bale slide.
Longer slides slid up the hill and across the floor until the bale came to a rest.
Longer slides were easier to measure.
As more washers were added the bale would slide up the hill stop and slide back down.
An observer positioned at the bottom of the track watched carefully to see how far the bale slide before it rolled back.
Three trials were made and recorded in a spreadsheet and graphed with the software.

Learners who participated were a mixed age group from 10-12 years old.