Archive for the ‘Science’ Category

Bowling with Momentum

Monday, September 12th, 2016

bowling-with-momentum

Today we are going on a field trip to a bowling alley: we will be bowling with momentum! Momentum is defined as the tendency of an object that is moving to continue moving.

How do you find momentum?

You find momentum by multiplying mass times speed:

momentum = mass x speed

In the case of my bowling ball, I saw on the TV screen above my head that my bowling ball was moving down the lane at 16 miles per hour. My bowling ball was 10 pounds. So the momentum was 160 pounds-miles/hour.

Bowling Experiment (video)

This post contains affiliate links. I was compensated for my work in writing this post.

We have been learning about momentum from Christian Kids Explore Physics by Bright Ideas Press, and this is one of the hands-on activities in the book. As you can see in the video, less speed or a lighter ball will decrease momentum. More speed or a heavier ball will increase momentum and be more likely to knock the pins down.

bowling

When my kids were toddlers, they would roll the bowling ball down the lane, and it sometimes stopped halfway down the lane because it lacked momentum. You need to give a ball enough speed so that the ball has enough momentum to keep going forward.

If the child had used more force (to increase the speed of the ball), it would probably not have come to a complete stop. (A heavier ball would have helped, too, but my toddlers could barely lift the lightest ball!)

bowling-physics

Why not go to a bowling alley this week and see if you can increase the momentum of your bowling ball and improve your score?

Flying Projectiles & Plotting Trajectories

Monday, September 5th, 2016

flying-projectiles-plotting-trajectories

Today we will be playing with flying projectiles and plotting trajectories. Yes, physics can be super fun when it’s hands-on!

First you will want to grab several objects that you don’t mind tossing into the air. We chose the following objects: a football toy, a small basketball, a frisbee, an over-sized toy clock, and a frozen cheese pizza.

Flying Projectiles Experiment (video)

This post contains affiliate links. I was compensated for my work in writing this post.

We got the idea to toss a pizza in the air as a projectile because of this quiz question from Christian Kids Explore Physics by Bright Ideas Press:

cheese-pizza

One of my sons insisted that a cheese pizza could very well be a projectile. Ha!

So what exactly is a projectile?

A projectile is something that can be sent flying through the air. How far the projectile flies through the air depends on three things:

  1. The speed of the projectile (how hard you throw the ball)
  2. The force of gravity (it pulls down on the object)
  3. The angle of launch (the higher the angle, the farther the object will go)

Then what is a trajectory?

A trajectory is the path of a projectile. If you want to plot the trajectory of a tennis ball rolling off a table, you will need the following items:

  • a tennis ball
  • a table
  • a measuring tape
  • masking tape
  • charts from the book

trajectory-experiment

As you can see in the video, we rolled the ball off the table with with slow, medium, and fast speeds, and we plotted those trajectories. (You mark the floor at the edge of the table with the masking tape to use that as a starting point to measure how far the ball flies through the air.)

We also dropped a ball straight down to see if there was any trajectory at all. You can see the results of our experiment in the video above. It was super fun!

plotting-trajectories-chart

The Speed of a Rotating Cookie

Monday, August 29th, 2016

speed-of-a-rotating-cookie

Today we are baking a gigantic cookie, and then we will spin it! We are attempting to determine the speed of a rotating cookie, and I will compare it to a merry-go-round.

First you need to go into your kitchen and bake a huge chocolate chip cookie.

baking-cookiesThis post contains affiliate links. I was compensated for my work in writing this post.

You can use your favorite cookie dough recipe. My daughter Rachel tells you how much of each ingredient she used to make her cookie:

This fun experiment is from Christian Kids Explore Physics by Bright Ideas Press, In the chapter on motion, the book describes how to figure out the speed of a merry-go-round. First you need to determine the circumference of the merry-go-round.

C = 2π r

The radius of the merry-go-round is 5 feet.

5 times 2 times 3.14 equals 31.4 feet. So the distance around the merry-go-round is 31.4 feet. That means every time Rachel goes around, she travels 31.4 feet.

Now we need to determine how fast the merry-go-round is going. My son pushed Rachel around as hard as he could while my other son timed 15 seconds. I counted how many times Rachel went around in 15 seconds. The answer was almost 4 times–3.75 times is more accurate, as you can see if you watched the video. 3.75 times 4 equals 15 revolutions per minute. (A minute has 4 segments of 15 seconds.)

To determine how many feet Rachel traveled in one minute while riding the merry-go-round, multiply the circumference by the speed. She traveled 471 feet per minute!

merry-go-round-physics

In the video I show you how to determine the speed of your rotating cookie at home, depending on how big it is and how fast you spin it. Who knew physics could be so fun and delicious!

Turning Potential into Kinetic Energy

Monday, August 22nd, 2016

turning-potential-into-kinetic-energy

In today’s experiment, we will be turning potential into kinetic energy as we hold various objects above a bucket of water and release them to see how far they splash.

Sounds fun, doesn’t it?

You will want to do this experiment outside on a sunny day. The person dropping the objects needs to be willing to get wet, especially when the person releases the heavier objects like the banana and the can of baked beans!

Turning Potential into Kinetic Energy (The Experiment)

Step 1: Gather supplies. You will need a large tub, a hose, a ruler, and various objects to drop into the water. We used a marshmallow, a grape, a nut, a quarter, a pine cone, a banana, and a can of baked beans.

splashing-experimentThis post contains affiliate links. I was compensated for my work in writing this post.

Step 2: Fill the tub with water and have someone hold a ruler on the side of the tub. Print out the chart on page 143 of Christian Kids Explore Physics by Bright Ideas Press, and clip it to a clipboard. Record your findings on the chart, or you can just call out how many inches the water splashed upwards.

splash-grape

Step 3: Drop each object and watch how far the water splashes. The objects with more mass have more potential energy. When an object is held above the water, there is potential energy in the object. Potential energy is converted into kinetic energy as soon as you release the object because it is now moving.

Let me describe it another way: A log of wood has potential energy. It’s just sitting there and doesn’t look like it has energy, but as soon as you light it on fire, the potential energy is converted into kinetic energy.

Energy will be released if something happens to an object with potential energy. As long as an object just sits there, it’s only potential. When movement or chemical change occurs, you now have kinetic energy.

Video of the Splashing Experiment:

Take a look at how far each of our objects splashed:

Hope you enjoyed our fun experiment!