Forces / Newton's Laws of Motion

Question 1

Newton’s first law of motion

Answer 1

An object continues in a state of rest or in a state of motion at a constant speed along a straight line, unless compelled to change by a net outside force.

Question 2

natural tendency of an object to remain at rest or in motion at a constant speed along a straight line
mass is a quantitative measure of this value

Answer 2

inertia

Question 3

vector sum of all forces

Answer 3

net force

Question 4

a greater net force is required to change the ____ of some object than others (i.e. Force might cause bike to speed up but not move an elephant)

Answer 4

velocity

Question 5

Newton’s Second law of motion

Answer 5

Whe na net force acts on an object of mass (m), the acceleration that results is directly proportional to the new force and has a magnitude that is inversely proportional to the mass
direction of the acceleration is the same as the direction of the net force

Question 6

Equation: Newton’s second law of motion (Force)

Answer 6

Force (net) = mass * acceleration = m * a

SI Unit: kg*m/s^2 = N (Newton)

Question 7

Only the component of Force _____ to the ground causes acceleration in the horizontal direction (i.e. across the ground)

Answer 7

parallel i.e. F(x) = F(horizontal)

Question 8

Newton’s third law of motion

Answer 8

whenever one body exerts a force on a second body, the second body exerts an oppositely directed force of equal magnitude on the first body
for every action there is an equal and opposite reaction

Question 9

Equation: Gravitational Force

Answer 9

F = G * M1 * M2 / r^2
Note: M1 and M2 = masses of two particles sep’d by distance r
G = Universal gravitational constant

Question 10

Universal Gravitational Constant (G)

Answer 10

G = 6.67 * 10 ^ -11 N * m^2 / kg^2

Units: N*m^2 / kg^2

Question 11

gravitational force that the earth exerts on an object

always acts downward, towards the center of the Earth

Answer 11

weight (of an object on Earth)

Question 12

Equation: Weight

Answer 12

W = G * M(e) * (m) / r^2 = m * g
Note: G = gravitational constant
M(e) = mass of the Earth
m = mass of the object
r = distance between the two masses (0 when object is one Earth)
g = acceleration due to gravity (10 m/s^2)

Question 13

one component of the force that a surface exerts on an object with which is it in contact
component that is perpendicular to the surface
opposes the weight of the object

Answer 13

Normal Force: F(n)

Question 14

If the object is motionless or moving at a constant velocity, then there must be _______ on the object.

Answer 14

zero net force on the object

Question 15

If the only force present is the weight of the object (m*g) then the normal force must be of _________ to the weight but in the ________ direction.

Answer 15

equal magnitude to the weight

opposite direction