newton's laws and inertia

Question 1

what is newton’s first law?

Answer 1

If the resultant force on a stationary object is zero, the object will remain stationary. If the resultant force on a moving object is zero, it will continue moving at the same velocity.

Question 2

what is needed to change the velocity of an object?

Answer 2

a resultant force

Question 3

an object is moving with a 50N force to the right, and a 50N force to the left. What is the resultant force and what effect does it have on the object?

Answer 3

The forces are balanced so the resultant force is zero, meaning that the object will continue moving at the same velocity.

Question 4

what is need for a constant speed?

Answer 4

a driving force and a resistive force, with the same force

Question 5

a train is moving at a constant velocity, what is the relationship between the driving and resistive force?

Answer 5

they are balanced

Question 6

what will a non-zero resultant force produce?

Answer 6

an acceleration or deceleration in the direction of the resultant force

Question 7

what is newton’s second law?

Answer 7

the acceleration of an object is proportional to the resultant force acting on the object and inversely proportional to the mass if the object

Question 8

what does newton’s second law mean?

Answer 8

the larger the resultant force, then the larger the acceleration
if the mass is larger, then the acceleration will be smaller

Question 9

An object has a resultant force of 10N, and another has a resultant force of 20N. What is the relationship for acceleration between the two objects?

Answer 9

The object with a force of 20N will experience twice the acceleration of the other object.

Question 10

Two objects have the same resultant force. One object has a mass of 1kg, and another has a mass of 2kg. What is the relationship for acceleration between the two objects?

Answer 10

The object with a mass of 1kg will experience twice the acceleration of the other object.

Question 11

what is the equation linking acceleration, mass and force?

Answer 11

Force (N) =mass (kg) x acceleration (m/s²)
F=ma

Question 12

calculate the force needed to accelerate an object with a mass of 5kg by 4m/s²

Answer 12

F=ma
F=5 x 4
F=20N

Question 13

A force of 50N is applied to an object with a mass of 0.5kg. Calculate the acceleration of the object.

Answer 13

a=F/m
a=50/0.5
a=100m/s²

Question 14

estimate the resultant force on a car as it accelerates from rest to a typical speed

Answer 14

typical speed 25m/s
takes 10s to reach this
a=v/t
a=25/10
a=2.5 m/s²

typical mass is 1000kg

F=ma
F=1000 x 2.5
F=2500N

Question 15

average acceleration from a main road to a motorway

Answer 15

2 m/s²

Question 16

average speed a car travels on a main road and a motorway

Answer 16

main road: 13m/s
motorway: 30 m/s

Question 17

inertia

Answer 17

objects will stay still or keep the same motion unless you apply a resultant force

Question 18

inertial mass

Answer 18

a measure of how difficult it is to change the velocity of an object

Question 19

inertial mass equation

Answer 19

m=F/a
the ratio of the force needed to accelerate an object, over the acceleration produced

Question 20

what is the difference between the force required to produce an acceleration for an object with a larger inertial mass compared to one with a smaller inertial mass?

Answer 20

the object with a larger inertial mass will require a larger force

Question 21

what is newton’s third law?

Answer 21

when two objects interact, the forces they exert on each other are equal and opposite

Question 22

give three examples of newton’s third law

Answer 22

1. canoeing-The paddle pushes onto the water. At the same time the water pushes back on the paddle. This force is equal in magnitude but opposite in direction.
2. rocket-When a rocket fires, the chemical reaction produces a downward push force on the hot exhaust gases. The exhaust gases exert an equal force on the rocket but acting in the opposite direction.
3. a book on a table in equilibrium-the normal contact force from the table is pushing up on the book and the normal contact force from the book is pushing down on the table