On the Move
You're late to class!! As you're running down the hall, using a reference point of your backpack, are you in motion?
What does Newton's First Law describe?
Law of Inertia: Objects at rest will stay at rest until acted upon by an outside force.
What's the speed of a frog if it was able to hop 2 meters in 1 second?
Speed = Distance / Time
Speed = 2 meters / 1 second
Speed = 2 m/s
T/F: Gravity is a contact force that brings objects back down to earth.
False! Gravity is non contact!
What are 2 examples of non contact forces?
Friction, gravity, magnetism, electricity.
Which law best explains why pushing backwards on a skateboard causes you to move forward?
It took you 30 minutes to walk to school and the trip was about 2 miles. What was your average speed for the whole trip?
0.066 miles per minute
What type of friction is applied when an object with wheels moves across a similarly smooth surface?
Rolling Friction
Your friend tells you that in science class, speed and velocity are synonyms (they mean the same things). Why is your friend wrong?
Which law best explains why you'd only be able to move heavy objects at slower speeds?
2nd Law: Law of Acceleration. Heavier objects require more force to move. So trying to move a very massive object at a high acceleration would need a crazy amount of force.
What force is required to move a jug of water that has a mass of 7 kg an acceleration of 2 m/s?
Force = Mass x Acceleration
Force = 7 kg x 2 m/s
Force = 14 N
What type of friction is applied to objects resting on a surface to keep them from moving?
Static friction
When Buzz Aldrin hit a golf ball off the moon, it shot into space and continued to fly at the same speed and same direction forever. Is the golf ball accelerating?
No, it is not changing velocity.
You're lifting boxes to help a friend move, and the past few boxes you've moved have been very heavy. You go to pick up another box using the same force you've been using to lift the others, but it turns out this one is way lighter! Using the 2nd Law, how would you describe the acceleration of this lighter box?
Using a large force to move an object with a low mass would mean it'd accelerate at very high speeds.
What would the acceleration on a skateboard be if you pushed it with a 30 kg puppy and a force of 10 N?
Force = Mass x Acceleration
10 N = 30 kg x A
10 N / 30 kg = A
0.33 m/s = A
Where would you have the most Gravitational Potential Energy?
a) On a high diving board
b) Right before you enter the water
c) When you're under water
A! The higher you are, the more potential energy you have.