Motion and Forces
Speed
-> An indicator of how fast something is moving.
-> Speed can be expressed with different units:
km/h , miles/h , m/s
-> Represented by the symbol "v"
Distance
-> The length of path traveled.
-> Units for distance :
km , m , miles , cm , lightyear , etc.
-> Remember: 1000 m = 1 km
-> Represented by the symbol "d"
Time Difference
->The amount of time elapsed, also known as the time interval.
-> Units for time:
h , min , s
-> Remember: 1 h = 60 mins, 1 min = 60 s, 1h = 3600 s
-> Represented by the symbol "Δt"
Speed, Distance, and Time
-> The relationship between speed, distance, and time is represented by the formula:
v = d
Δt
-> Note: the units must MATCH!
Examples:
1) What is the speed of a dog that can run 40 m in 8.0 s?
d = 40 m
Δt = 8.0 s
v = ?
v = d
Δt
= 40 m
8.0 s
= 5.0 m/s
2) How long will it take a car going 105 km/h to travel 250 km?
d = 250 km
Δt = ?
v = 105 km/h
v = d
Δt
105 km/h = 250 km
Δt
105 km/h x Δt = 250 km
Δt = 250 km
105 km/h
Δt = 2.38 h
What is a force?
-> A force is a pull or a push.
-> Must be a size and a direction.
-> Measured in Newtons (N).
-> Symbol used for force is "F".
Weight (force due to gravity)
-> All objects are subjected to the force of gravity on Earth.
-> The symbol for force due to gravity is:
Fg
Mass vs. Weight
-> Mass is the quantity of matter in an object. It does not change.
-> Weight is the force due to gravity acting on an object.
-> On another planet:
-> Mass is the same
-> Weight changes
Calculating Weight
-> There is a relation between weight and mass.
-> The formula is:
Fg = mg
where Fg = weight ( N )
m = mass ( kg )
g = gravitational constant ( 9.8 N/kg (on Earth))
example:
1) What is the weight of a 50 kg box?
Fg = mg
= ( 50 kg ) ( 9.8 N )
kg
= 490 N
2) Gravity exerts a force of 200 N on a toy. What is the mass of the toy?
Fg = mg
200 N = m ( 9.8 N )
kg
200 N = m
9.8 N/kg
20.4 kg = m
3) A hammer has a weight of 12.0 N on Mars, where the gravitational constant is 3.8 N/kg.
Find the hammer's weight on Earth.
A. Fg = mg
12.0 N = m ( 3.8 N/kg)
3.2 kg = m
B. Fg = mg
= ( 3.2 kg ) (9.8 N/kg)
= 31.4 N
4) A ball has a weight of 29.4 N on Earth. This heavy ball is sent to Venus, where it has a weight of 13 N.
What is the gravitational constant of Venus?
A. Fg = mg
29.4 N = ( m ) ( 9.8 N/kg)
3 kg = m
B. Fg = mg
13 N = ( 3 kg ) ( g )
4.3 N/kg = g
Simultaneous Force
-> Sometimes, multiple forces can be acting on an object at the same time.
-> We must take the direction of forces into consideration when we combine forces.
-> It is represented by -------->
Net Force
-> The net force is the addition of forces applied to an object.
-> An indicator of how fast something is moving.
-> Speed can be expressed with different units:
km/h , miles/h , m/s
-> Represented by the symbol "v"
Distance
-> The length of path traveled.
-> Units for distance :
km , m , miles , cm , lightyear , etc.
-> Remember: 1000 m = 1 km
-> Represented by the symbol "d"
Time Difference
->The amount of time elapsed, also known as the time interval.
-> Units for time:
h , min , s
-> Remember: 1 h = 60 mins, 1 min = 60 s, 1h = 3600 s
-> Represented by the symbol "Δt"
Speed, Distance, and Time
-> The relationship between speed, distance, and time is represented by the formula:
v = d
Δt
-> Note: the units must MATCH!
Examples:
1) What is the speed of a dog that can run 40 m in 8.0 s?
d = 40 m
Δt = 8.0 s
v = ?
v = d
Δt
= 40 m
8.0 s
= 5.0 m/s
2) How long will it take a car going 105 km/h to travel 250 km?
d = 250 km
Δt = ?
v = 105 km/h
v = d
Δt
105 km/h = 250 km
Δt
105 km/h x Δt = 250 km
Δt = 250 km
105 km/h
Δt = 2.38 h
What is a force?
-> A force is a pull or a push.
-> Must be a size and a direction.
-> Measured in Newtons (N).
-> Symbol used for force is "F".
Weight (force due to gravity)
-> All objects are subjected to the force of gravity on Earth.
-> The symbol for force due to gravity is:
Fg
Mass vs. Weight
-> Mass is the quantity of matter in an object. It does not change.
-> Weight is the force due to gravity acting on an object.
-> On another planet:
-> Mass is the same
-> Weight changes
Calculating Weight
-> There is a relation between weight and mass.
-> The formula is:
Fg = mg
where Fg = weight ( N )
m = mass ( kg )
g = gravitational constant ( 9.8 N/kg (on Earth))
example:
1) What is the weight of a 50 kg box?
Fg = mg
= ( 50 kg ) ( 9.8 N )
kg
= 490 N
2) Gravity exerts a force of 200 N on a toy. What is the mass of the toy?
Fg = mg
200 N = m ( 9.8 N )
kg
200 N = m
9.8 N/kg
20.4 kg = m
3) A hammer has a weight of 12.0 N on Mars, where the gravitational constant is 3.8 N/kg.
Find the hammer's weight on Earth.
A. Fg = mg
12.0 N = m ( 3.8 N/kg)
3.2 kg = m
B. Fg = mg
= ( 3.2 kg ) (9.8 N/kg)
= 31.4 N
4) A ball has a weight of 29.4 N on Earth. This heavy ball is sent to Venus, where it has a weight of 13 N.
What is the gravitational constant of Venus?
A. Fg = mg
29.4 N = ( m ) ( 9.8 N/kg)
3 kg = m
B. Fg = mg
13 N = ( 3 kg ) ( g )
4.3 N/kg = g
Simultaneous Force
-> Sometimes, multiple forces can be acting on an object at the same time.
-> We must take the direction of forces into consideration when we combine forces.
-> It is represented by -------->
Net Force
-> The net force is the addition of forces applied to an object.
examples_net_force.docx | |
File Size: | 13 kb |
File Type: | docx |
Definitons:
Frame of reference: what we compare motion to.
Position: where an object is.
Displacement: length of path traveled.
Time interval: time elapsed.
Speed: how fast an object is moving.
Velocity: how fast and in what direction.
Frame of reference: what we compare motion to.
Position: where an object is.
Displacement: length of path traveled.
Time interval: time elapsed.
Speed: how fast an object is moving.
Velocity: how fast and in what direction.