Laws of Motion
An object at rest tends to stay at rest and an object in motion tends to stay in motion with the same speed and in the same direction unless acted upon by an unbalanced force.
First Law of Motion. Law of Inertia
A complete description of your position includes a distance, a direction, and a _____________.
reference point
What is the distance traveled per unit of time?
speed
If the reference direction is to the right and a force of 10 N acts to the left while another force of 78 N acts to the right, how much net force is acting on the object?
68 N to the right
How far was the bus from its starting point after 9 seconds?
10 meters
Equal force in each direction, the net force is zero. Will there be motion? Yes or no?
Yes!
You are driving a car and your speed does not change
constant speed
This is the natural tendency of objects to keep on doing what they're doing or to not move at all.
Inertia
•A bus travels at a constant speed of 50 km/h. How long will it take to travel 200 km?
200km / 5km/hr
4 hours
How long did the bus stop throughout its journey?
AB = 5s
CD = 3s
EF = 4s
Total = 12s
Calculate the net force. (Insert Picture)
5N
Distance in relation to the starting point
Discplacement
A straight line in a graph means
Stationary or at rest
What force is needed for an object with a mass of 15 kg to accelerate at 20 m/s2?
f=ma
f=(15)(20)
f=300N
A truck travels 60 kilometers in the first hour and 80 kilometers in the second hour. What is the average speed of the truck?
Average speed= Total distance/total time
Average speed=60+80= 140/ 1hour + 1 hour = 2Hr
Average speed= 140/2
Average speed = 70km/hr
Explain the second law of motion
More mass needs more force.
An object accelerates when its velocity changes as a result of increasing speed, decreasing speed, or a _________________.
change in direction
Speed in a certain direction
velocity
You need to get to your classroom 300 meters away, and you can walk in the hallways about 2m/s. How much time will it take to get to your class?
time = Distance/speed
time 300m / 2m/s
time= 150 s
A car is moving towards northwest 8500m in 1.5 hours. What is his average velocity?
Velocity= 8500m = 6.5km
Velocity=8.5km/1.5hr
Velocity=5.66km/hr
According to Newton’s third law of motion, when one object applies a force on a second object, the second object applies an _______ force in the _________ direction on the first object.
equal - opposite
Draw a distance-time graph for an object moving at constant speed.
straight line with upward slope
This is a force of resistance between 2 objects touching each other.
friction
What is work done if a 10N force moves a distance of 5m?
W=fxd
W=10x5
W= 12Joules
At which point did the bus travel faster OA or DE? Prove your answer.
OA = 10m/5s = 2m/s
DE = 5m/5s = 1m/s
OA is faster.