Chapter 5: Force & Motion I

Question 1

What is dynamics?

Answer 1

It is the study of the cause of motion.

Question 2

What is a force?

Answer 2

An interaction between an agent (exerts the force) and an object (experiences the force) that can change the object’s velocity.
SI unit: newton (N).

Question 3

Is force a vector quantity?

Answer 3

Yes!

Question 4

What is mass?

Answer 4

A measure of a particle’s inertia.
SI unit: kilogram (kg)

Question 5

Is mass a vector quantity?

Answer 5

No!

Question 6

What is inertia?

Answer 6

The tendency to resist change in velocity.

Question 7

What is Newton’s First Law of motion?

Answer 7

If the net force acting on an object is equal to zero, then the object’s velocity cannot change.

Question 8

What is Newton’s Second law of motion?

Answer 8

A cause-and-effect relationship. When a net force acts on an object of mass m, then the object will accelerate. a = (Fnet)/m

Question 9

What is Newton’s Third Law of motion?

Answer 9

If two particles, A and B, interact, then the force on A due to B and the force on B due to A have equal magnitudes but opposite directions.

Question 10

What is an inertial reference frame?

Answer 10

Any reference frame in which Newton’s first law is valid.

Question 11

Any reference frame fixed to Earth is (approximately) ___.

Answer 11

Inertial

Question 12

Any reference frame moving at a constant velocity relative to Earth is (approximately) ___.

Answer 12

Inertial

Question 13

Any reference frame accelerating relative to Earth is ___.

Answer 13

Non-inertial

Question 14

What is force due to gravity?

Answer 14

The force acting on a particle due to its gravitational interaction with the nearest astronomical body. |Fgrav| = mg

Question 15

___ is the gravitational field strength of an astronomical body.

Answer 15

g

Question 16

On Earth, g = …

Answer 16

9.8 N/kg

Question 17

While mass is a scalar quantity that is the same everywhere, weight is…

Answer 17

The magnitude of a vector quantity (mg) that depends on the local value of g.

Question 18

What is tension force?

Answer 18

The force a taut rope exerts on any object to which it is attached.

Question 19

There (is)/(is not) a specific mathematical formula for tension force.

Answer 19

There is not–it must be found using Newton’s second law.

Question 20

What is normal force?

Answer 20

A reaction to two surfaces in contact. Just like tension force, there is no specific formula for it.

Question 21

A normal force acts ___ to a surface.

Answer 21

Perpendicular

Question 22

Newton’s third law is ALWAYS referring to two particles, and is true regardless of ___.

Answer 22

The relative size/masses of the two particles.

Question 23

When a particle is in ___, it has no acceleration.

Answer 23

Equilibrium