Teacher’s Guide


If someone drops 2 objects indigenous the same height, one heavy, one light, which one will certainly hit the floor first? If you room like many people, you might instinctively choose the more heavier object. And also why i will not ~ you? after all, rocks loss faster 보다 feathers. There room other factors besides weight that influence the rate of an item as the falls. This experiment will assist students discover those factors, such together gravity and air. Students will usage both your eyes and their ears to figure out how mass affects the rate at i m sorry something falls.

You are watching: Which will hit the ground first a heavy or light object

For more information and ideas on just how to implement the task in your classroom check out the video.

Key Terms

Mass: A measure up of the lot of stuff (or matter) an item has. No to be puzzled with weight or volume. Mass only says how much really stuff there is, no how large an thing is or how tough something is pulling on it.

Weight: massive (amount that stuff) times how tough the planet is pulling on that (gravity). This method that her weight ~ above the moon will certainly be 1/6 of the on earth (gravity ~ above the moon is 0.166 times of that on Earth). However, your mass will still be the same.

Force: The press or pull an object feels since of interaction with other objects. If the communication stops, climate there is no force. The is formally characterized as mass time acceleration. Because that example, gravity is a force that to represent the traction the earth has on all objects.

Velocity: A measure up of how fast something is walk in some specific direction. No to be confused with speed, i beg your pardon is only how rapid something is moving. “The automobile was walk 65 mph southern on I-95” is a measure up of velocity. “The rollercoaster was relocating at 65 mph as soon as Billy acquired sick” is a measure of speed.

Acceleration: How quick the velocity is changing. As soon as something accelerates it changes how quick it is going or the direction in which the is moving. For a positive readjust in acceleration method that the thing is relocating faster, a vehicle going native 30 mph to 40 mph. A an adverse change method the object is moving slower, the vehicle is going indigenous 40mph to 30 mph. Finally, a change in the direction the the object’s velocity without an altering speed, such together if a automobile is relocating North and also turns eastern still moving, then the car sped up because the direction that the car’s velocity changed. Remember that velocity is a vector with direction and magnitude, therefore changes in any (or both) the those factors will produce an acceleration.

Air resistance: The pressure air exerts top top something moving through it. When an object with a enlarge surface falls through air, that feels much more air resistance. Waiting resistance walk not rely on the massive of the object.

Before the activity students have to know:

Gravity indigenous the planet makes things autumn by pulling objects towards the ground

There’s a difference in between weight and also mass.There’s a difference between speed, velocity and acceleration.That a force is mass time acceleration.When something falls through air it experience air resistance.

AFTER the task students have to know:

How fixed affects the speed at which objects fall.Why a hammer and a feather will autumn at the same price on the moon yet not top top Earth.

The science Behind fallout’s Objects

If someone verified you 2 spheres that the exact same size however with different masses, say 1g and 10kg, and also asked which would certainly hit the ground an initial after being dropped native the Leaning Tower of Pisa, what would certainly you say? If she like many people, you would certainly say the 10kg round would struggle the soil first. Aristotle said so too, and for 1,000 year everyone believed him. However doing the experiment would show you, besides a good view of Pisa, the in fact, both spheres struggle the ground in ~ the very same time.

This is precisely what Galileo did, mirroring the civilization that objects of different masses autumn at the same rate. (This is additionally a an excellent example of why it is necessary to perform experiments yourself and not to just take who else’s word because that it.) to start knowledge why Galileo to be right, we require to know the difference between several physics words that are regularly jumbled together and confused: mass, weight, speed, velocity, acceleration, and also force.

Let’s start with mass and also weight. Massive is the lot of stuff things has. Mass and weight space not the exact same thing: the massive of things will stay the exact same no matter where the is in the Universe, yet weight will certainly not. If I had some amount of stuff, say an apple, and also took that from the earth to the Moon, I would certainly still have the same amount of stuff: one to apologize (assuming i didn’t gain hungry on the trip). No matter where I placed that one apple, i will constantly have the very same amount the apple, uneven I eat it. This way that right here or on the Moon, my apple has the same mass. Mass has the unit of kilograms.

Now, load is the amount of mass time the force of gravity, or how difficult a world is pulling things towards itself. Going ago to ours apple, that apple would be a lot less complicated to lift and also put in my mouth ~ above the Moon 보다 on Earth, right? The earth pulls top top the apologize harder than the moon would, because the traction of the earth (gravity) is stronger than the of the Moon. Even though I have the very same amount that stuff, the exact same mass, the weight of my apple is greater on planet than that is on the Moon. Weight is mass times acceleration, this acceleration is native the gravity pressure that pulls the objects toward the ground. Weight has actually the unit of Newtons, i beg your pardon is the units of mass (kilograms) times the systems of acceleration. However how execute we sometimes gain units the mass when we ask because that the weight of things? that is because the scale we usage to measure up weight factor in the acceleration the the traction of the planet on the object. This factor is a continuous on the Earth, meaning that the is always the exact same if you room on Earth. If i were on the moon and also my to apologize weighs .25 Newtons, ns will need to know the worth of the acceleration of gravity on the moon to find its mass.

Now on to velocity, speed, acceleration and force. Velocity and speed room two various things, but the difference is really small. Velocity gives much more information than rate does, due to the fact that it tells us how rapid something is moving in a particular direction. Speed is how rapid something is going, however says nothing around the direction of that motion.. Acceleration says how much the velocity is changing in a details direction. If something has actually a constant velocity, say moving south in ~ 65 mph, there is no acceleration.

Now how can you do something accelerate? to accelerate, an item needs to feel a force, that means a pull or a push. If you kick a football with some quantity of force, the soccer is walk to change its velocity, which way it’s accelerating. Pressure is mass times acceleration. This means that pressure is the quantity of stuff times how difficult it is being propelled or pulled. The enlarge the pressure (the stronger the kick), the bigger change in the football’s acceleration, because its mass doesn’t change.

When something falls, that falls due to the fact that of gravity. Since that object feels a force, that accelerates, which means its velocity it s okay bigger and also bigger together it falls. The stamin with which the earth pulls on something in the kind of gravity is a type of acceleration. Planet pulls on whatever the precise same amount. Everything gets increased towards the planet exactly the very same way. The pressure that objects feel might be different due to the fact that they have various masses, but the acceleration on earth they suffer is precisely the same. Load is the pressure that acts upon the mass due to gravity, since it is exactly how much stuff over there is times the acceleration in ~ which is pulled towards the Earth, or any planet or moons. Due to the fact that Earth gives whatever the specific same acceleration, objects with different masses will certainly still hit the ground at the same time if they room dropped indigenous the exact same height.

The an initial time you speak that, nobody will believe you due to the fact that everyone has actually dropped a marble and a feather in ~ the same time and also they struggle the floor at various times. The is not due to the fact that of distinctions in the acceleration - i beg your pardon is consistent on Earth, the is since air is pushing versus the object in the contrary direction the earth is pulling. This force is brought about by air resistance.

The less massive the thing is, the an ext the pressure of air resistance slow the object down as the falls. If two objects were dropped top top the moon, whereby there is no air, lock would fall at the same rate no matter just how much they differ in mass. The form of the object can influence how lot it is affected by wait resistance. Because that example, if you drop a item of document horizontally, it has actually a the majority of surface the is exposed come the waiting resistance. However if friend drop the file vertically, ~ above the thin side, climate there is much less surface exposed come the waiting resistance. This means that, in the position, the paper will feel much less push native the air and also the very same pull from the Earth. Two pieces of paper with the exact same mass dropped native the same height but with one in the horizontal position and the other in the vertical position will no hit the floor at the same time.

Astronaut Neil Armstrong walk an experiment on the moon to convince everyone that Galileo to be right, that 2 objects of different mass and shape -in this case a feather and a hammer - in the lack of waiting resistance will certainly hit the ground in ~ the same time.

Experiment 2 that you will be performing, two objects of various masses that roughly experience the very same air resistance will certainly be dropped and also hopefully to convince your children that mass has nothing to perform with how things fall.

Experiment 1

Materials2 equal-sized pieces of paperChair or table (or both)A leader or metric tape (optional)Beam balance (optional)A camera to document the experiment (optional)A chronometer or something come measure the moment (optional)

In the student’s overview we have asked the student to architecture their very own experiment to check if two objects that the very same mass however different form hit the ground in ~ the exact same time. The idea is to encourage them to be creative, come understand exactly how to style experiments, and to think favor scientists and also engineers. Lock are provided a set of materials that they deserve to use to perform their experiments. This is to prompt them, however they should be allowed to usage other materials in your design. Together the teacher, you deserve to ask prompting concerns to acquire them come think around the different elements of the experiments. Below are the full instructions because that one possible design.

The score of the experiment is for students to recognize that mass is no a variable that affects how objects fall, that they an alert the form matters and also why it matters. Crumpling the document or changing the direction in which the document is dropped can support those ideas. They require to figure out which variables they should regulate for, for example dropping the files at the same time or the existence of a strong air current, and consistency the the repeated experiments.

We asking the students to monitor the scientific method to style the experiment.

The scientific an approach has five straightforward steps, plus one feedback step:

Make one observation.Ask a question.Form a hypothesis, or testable explanation.Make a prediction based upon the hypothesis.Test the prediction.Setting up


Take the 2 pieces of paper and crumple one right into a ball.If you have actually a beam balance, find the massive of each item of paper. Create those values on her notesMeasure the elevation from which you will certainly drop the piece of papers. Make certain it is the same height. Compose the elevation value on your notesGet her timer and also camera prepared for recordingCome up v a hypothesis: Which piece of file do girlfriend think would hit the floor first? The lighter one or the heavier one?Drop the piece of file at the same time

Students must reflect on exactly how the masses that the two pieces of document were the same, yet the crumpled item hit the ground first. Why?

Experiment 2

For this experiment students space asked to architecture a way to test if 2 objects of different mass but comparable shapes fight the ground at the exact same time. They have been offered a different collection of products from Experiment 1. In this case there are other variables to manage for, such as how comparable or various shapes influence the an outcome and the difference in mass between the two objects.If the massive is dual but the form is the same, will certainly the objects struggle the floor in ~ the same time? as with Experiment 1, us have provided you a feasible set up for the experiment. Yet again, students need to have freedom to develop their very own designs.

Materials2 balls similar in size but different massive 2 aluminum tart pansChair or table (or both)A ruler or metric ice cream (optional)Beam balance (optional)A chronometer or something come measure the moment (optional)A camera to record the experiment (optional)

In the kit over there are various sets of balls, repeat the experiment with all the possible wooden and rubber balls combinations. Make sure to brand the balls and also measure them come make an excellent comparisons.

If you space working at home and do not have actually the specific materials, friend can constantly substitute the balls through clay or playdough (see argued resources for a cooking recipes of homemade playdough). If you perform not have actually either clay or playdough, then find two objects roughly the home that have the same shape however different weights. Because that example, two the same water bottles, one full and also the other one with much less water or no water. The objective of this experiment is to check if objects with various masses yet the same shape autumn at the very same time. Rather of aluminium cake pans you have the right to use aluminum silver paper or any other kind of paper/foil that will develop a sound when the reduce objects fight them.

As with activity 1, we ask the students to monitor the scientific technique to design the experiment.

Setting upPlace the two tart pans ~ above the floor, bottom up, around a foot apart.Select 2 equal size ballsIf you have actually a beam balance, discover the fixed of the two balls and write those values on her notesGet her timer and also camera prepared to record your experimentCome up with a hypothesis: i m sorry ball do you think would fall faster? The lighter one or the heavier one?Drop the balls at the exact same timeHow countless bangs did you hear on the tart pans each time girlfriend dropped the balls

Students have to pay attention to how many bangs lock heard every time lock dropped the balls. Walk it rely on how different the masses that the balls were? Which ball hit the floor faster?

Next Generation of scientific research standards:

5-PS2-1. Assistance an dispute that the gravitational force exerted by earth on objects is command down.

MS-ESS1-2. Develop and also use a version to describe the role of gravity in the movements within galaxies and the solar system.

Corresponding expansion Activities



Suggested Resources

Videos because that younger children

Gravity & complimentary Fall

Danger! fall Objects

Simulations & Videos:

Was Galileo Right?: investigate the effect of heaviness on objects of assorted masses during cost-free fall. Guess what the position-time and velocity-time graphs will certainly look like. Compare graphs because that light and heavy objects.

Free fall Model: This simulation enables students to research the motion of an item in free fall.

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Free fall Fall air Resistance: This simulation allows students to to compare the movement of totally free falling objects with and without the affect of wait resistance.