Vocabulary
The amount of matter in an object is called ______.
Mass
Two sleds are being pushed on a flat surface. One sled has a mass of 5 kg, and the other has a mass of 10 kg. Both sleds are pushed with the same force of 50 N. Which sled will accelerate more easily?
The sled with less mass will accelerate more quickly.
What is the formula for calculating average speed?
average speed= distance traveled divided by travel time
A soccer ball rolls on the ground, but friction begins to slow it down. After a while, it hits a fence. Which of Newton's Laws of Motion explains why the ball remained in motion until it experienced gravity and then hit the fence?
Newton's First Law of Motion (The Law of Inertia)
TingTing is pushing a box with a force of 50N. IngIng is pulling the box with a force of 50N. Is the box moving?
Yes
The tendency of an object to resist a change in motion is known as ______.
inertia
What is the formula that shows how force, mass, and speed are connected?
Force=mass x acceleration or F=ma.
A car travels 60 kilometers in 1 hour. What is its average speed?
60 kmph
A rocket launches into space by pushing exhaust gases downward. The upward acceleration of the rocket is equal to the force of the downward push. Which law explains how the rocket moves upward as gases are pushed down?
Newton's Third Law of Motion (Action and Acceleration)
True or false: Objects with large mass move more quickly and easily than objects with less mass.
False
speeding up, slowing down, changing direction
If an object’s weight doubles while you're pushing it with the same force, what happens to its acceleration?
It slows down and becomes harder to push.
A runner goes 100 meters in 10 seconds. What is their average speed?
10 meters/second
Two friends push a heavy box. One friend pushes harder, and the box moves faster.
Question: What law describes how the box's speed changes with the amount of force applied?
Newton's Second Law of Motion (F=ma)
In a tug-o-war game between elementary students and middle school students, the elementary students pull the rope to the left with a force of 230N. Six middle school students pull in the opposite direction with the following forces: -3 N, -12 N, -20 N, -10N, -8N, and -90N. Who is winning, the elementary students, or the middle school students?
The elementary students are winning because the middle school students only have a net force of -143N, which is not enough to pull the rope in their direction.
Velocity is the _____ of an object in a particular ______.
speed + direction
If you push a 1 kg ball and a 5 kg ball with the same force, what happens to their speeds?
The 1 kg ball will go faster than the 5 kg ball.
A train moves 150 kilometers in 3 hours. What is its average speed?
50 kilometers/hour
Scenario: A car has a mass of 1,200 kg and accelerates at a rate of 3 m/s².
Question: What is the force applied to the car?
Force=Mass×Acceleration=1,200kg×3m/s2=3,600N
A parachute is descending at a slow, constant speed. The air resistance acting on it is 180 N. What could the force of gravity on the parachute be? [a. 180 N] [b. 130 N] [c. 240 N] [d.4,500 N]
c. 240 N
Give an example of an object experiencing inertia.
Answers will vary.
Two very large boulders (rocks) are rolling down a hill together. The first boulder has a mass of 500 kilograms, and the second boulder has a mass of 1,200 kilograms. Which boulder would be harder to stop, and why?
The larger boulder would be harder to stop because it takes more force to change the acceleration of an object with large mass than it does to change the acceleration of an object with little mass.
Who is the faster runner?
Emily's average speed: 200 m / 25 s = 8 m/s
Jake's average speed: 400 m / 50 s = 8 m/s
Scenario: A bicycle with a mass of 15 kg is being pushed, causing it to accelerate at 2 m/s².
Question: What is the force applied to the bicycle?
Force=Mass×Acceleration=15kg×2m/s2=30N
A truck has a mass of 1,000 kilograms when empty. A pile of rocks weighing 500 kilograms is added to the truck. If the engine exerts a force of 30,000 N, how much will the truck accelerate? Use the formula a=F/m and write your answer in m/s².
20 m/s²