Newton's 1st Law (Inertia & Motion)
A magician pulls a tablecloth out from under dishes, and the dishes remain in place. Which law explains this?
Newton's First Law: an object at rest remains at rest unless acted on by an outside force
If a baseball and a bowling ball are thrown with the same force, what happens?
The baseball will speed up faster due to its lower mass
Two equal forces of 500 N pull in opposite directions on a moving bus. What describes the motion of the bus?
It moves at a constant speed because the forces are balanced
A book sits completely still on a flat table. A student applies a 5N force pushing to the right, while friction applies a 5N force to the left. What is the net force acting on the book, and are the forces balanced or unbalanced?
0N (Balanced). Because the opposing forces are equal in strength, the net force is zero and the object remains at rest.
You push a heavy box across the room, and friction slows it down as it slides. Are pushing forces and friction examples of contact forces or non-contact forces?
Contact forces. They require physical touching between objects to interact.
A student ties stones of different masses (170 g, 82 g, 111 g) to identical toy cars and pushes them with equal force. What property is demonstrated?
The more mass an object has, the more inertia it has)
What modification generates the largest increase in a racecar's acceleration?
Reduce the overall mass of the vehicle by half
Two students pull on a rope with 100 N in opposite directions. If the student on the left increases her force to 125 N, how will the rope's motion change?
It will go from motionless to leftward acceleration due to unbalanced forces
Two dogs pull on a chew toy in opposite directions. Dog A pulls to the left with a force of 15N, and Dog B pulls to the right with a force of 22n What is the net force acting on the toy, and which direction will it move?
7N to the right (Unbalanced). Subtract the smaller force from the larger force
22N-15N = 7N in the direction of the stronger pull.
A dropped apple accelerates downward toward the floor without anything physically touching it. What type of force is gravity?
Non-contact force (or action-at-a-distance force). Gravity exerts a pull across a field without needing physical contact.
A stone speeds up as it falls (Scenario 1), while a bike slows down when braking (Scenario 2). What forces cause these changes?
Scenario 1 is caused by gravity, and Scenario 2 is caused by friction
What net force acts on a 1200kg car accelerating at 3 meters per second squared
F=ma
F= 1200 x 3
F= 3600N
A student sits in a passenger seat of a car moving forward at $50\text{ mph}$. Relative to the car seat, the student is not moving; relative to a tree on the side of the road, the student is moving at $50\text{ mph}$. What acts as the reference point that makes the student appear stationary?
The car seat (or the inside of the car). An object's observed motion depends entirely on the chosen reference point.
A 40kg sled is being pulled to the east by two children. One child pulls with 30N and the other child pulls with 20N in the same direction. A frictional force of 10N resists their effort to the west. What is the net force on the sled?
40N to the east (Unbalanced).
Combine forces in the same direction 30N + 20 N = 50N east and subtract opposing friction 50N - 10N = 40N east
Identify which two forces in this list are non-contact forces: Friction, Magnetic Force, Applied Push, Electrostatic Force, Normal Force.
Magnetic Force and Electrostatic Force. Both can attract or repel objects across a distance without physical contact
A space probe is traveling through deep space far away from any stars, planets, or atmospheric friction. The crew turns off the engines completely. What will happen to the motion of the space probe over time, and which concept of Newton's First Law explains this?
A) The probe will gradually slow down and eventually stop because an object requires continuous force to maintain motion.
B) The probe will immediately stop moving as soon as the applied forward force becomes zero.
C) The probe will continue moving in a straight line at a constant speed indefinitely because no net external force acts on it to change its state of inertia.
D) The probe will begin to orbit backward because the loss of engine force creates a negative unbalanced force.
C (The probe will continue moving in a straight line at a constant speed indefinitely...)
A student pushes a 10kg box with 30N of force against a 10N fricitional force. What is the acceleration?
Net Force 30N-10N = 20N
a= F/m
a= 20N/10kg
A ladybug travels 0.10 meters relative to its starting point (Point 1) in 5 seconds. What is its speed relative to that point
0.02 m/s
Speed= Distance/time
speed= 0.10m/5s
During a game of tug-of-war, Team A pulls to the left while Team B pulls to the right.
Player 1 on Team A pulls with $180\text{ N}$ of force.
Player 2 on Team A pulls with $220\text{ N}$ of force.
Player 1 on Team B pulls with $210\text{ N}$ of force.
Player 2 on Team B pulls with $190\text{ N}$ of force.
A third player joins Team B and adds an extra force. If the flag in the center of the rope remains completely motionless, how much force is the third player exerting, and are the overall forces balanced or unbalanced?
A)10N; Unbalanced
B) 0N; Balanced
C) 20N; Balanced
D) 400N; Unbalanced
B 0N; Balanced)
A paperclip rests on a table. A magnet held $2\text{ cm}$ above the table pulls the paperclip up into the air. Name the non-contact force pulling the paperclip up and the contact force that was supporting it while it rested on the table.
The magnetic force pulled it up (non-contact), and the normal force supported it on the table (contact).