First Law
After a cannonball is fired into frictionless space, the amount of force needed to keep it going equals. WHY?
Zero, since no force is necessary to keep it moving
Because objects in motion stay in motion (UNLESS acted on by an outside NET force)
Which has more mass, a kilogram of feathers or a kilogram of iron?
Neither - they are both the same mass
A player hits a ball with a bat. The action force is the impact of the bat against the ball. What is the reaction force?
The force of the ball against the bat
A 10 kg brick and a 1 kg book are dropped in a vacuum. The force of gravity on the 10 kg brick is ___ x's as much force as the force on the 1 kg book.
10 times as much as the force on the 1 kg book. OR 100 N.
Friction is a force that always acts
opposite to an object's motion
The law of inertia applies to objects with which two kinds of motion?
No motion (at rest)
Constant motion
How does the acceleration of an object change in relation to its mass when the force is held constant? It is ________ proportional
Inversely
A person is attracted towards the center of Earth by a 440 N gravitational force. The force with which Earth is attracted toward the person is
440 N
Compared to its weight on Earth, a 10 kg object on the moon will weigh ____ than it weighs on earth
Less
You pull horizontally on a 50 kg crate with a force of 450 N and the friction force on the crate is 250 N. The acceleration of the crate is
4 m/s2
One object has twice as much mass as another object. The first object also has twice as much _______. This is because _____ is mass dependent.
Inertia
A girl pulls on a 10 kg wagon with a constant force of 20 N (ignoring friction). What is the wagon's acceleration?
2 m/s2
A high school student hits a nail with a hammer. Name the action-reaction pairs happening here.
On the surface of Jupiter, the acceleration due to gravity is about 3 times that on Earth. How much would a 0.40 kg rock weigh on Jupiter?
12 N
When the angle of an incline with a block resting on it increases, the normal support force (increases), (decreases), (stays the same)?
It decreases
Suppose the force of friction on a sliding object is 25 N. The force applied that is needed to maintain a constant velocity is _________ N
25
A force of 3 N accelerates a mass of 3 kg at a rate of 1 m/s2. The acceleration of a mass of 6 kg acted upon by a force of 6N is (twice as much) (half as much) (the same) acceleration as the 3 kg mass experienced?
The same
According to Newton's third law, if you push gently on something, it will push
gently on you
On the surface of Jupiter, the acceleration due to gravity is about 3 times that of Earth. What would be the mass of a 170 kg rock on Jupiter?
170 kg
A 400,000 kg airplane in takeoff uses the 40,000 N thrust of EACH one of its FOUR engines. What is the acceleration of the plane during takeoff?
0.4 m/s2
A box is dragged without acceleration in a straight-line path across a level surface by a force of 13 N. What is the frictional force between the box and the surface?
13 N
Suppose a cart is being moved by a force. If suddenly a load is dumped into the cart so that the cart's mass doubles, what happens to the cart's acceleration?
It halves
A bug meets its unfortunate demise when it encounters the windshield of a truck traveling at 10 m/s2. Which experiences the greater force in the collision?
Neither; both are the same
A 20 kg object on the moon experiences a gravitational pull of 1.7 N/kg. What is the weight of the object on the moon?
34 N
A 3 kg block is pulled across a table by a string with force of 40 N. The block experiences a friciton force of 5 N. What is the acceleration of the block?
11.66 m/s2