Transcript 2_5 Falling Objects

2_5 Falling Objects
27 March 2016
What are the missing terms?
Force = mass x ___________
Speed = _______
time
Velocity is _______ in a given _________
Acceleration = ________________
time
2_5 Falling Objects
Force = mass x acceleration
Speed = distance
time
Velocity is speed in a given direction.
Acceleration = Change in velocity
time
27 March 2016
2_5 Falling Objects
27 March 2016
• What is the difference between mass
and weight?
• What is the terminal velocity?
The World record
downhill skiing
record is 250.7
km/h! How does this
suit allow the skier
to achieve this?
Mass and Weight
Weight (N) = mass (kg) x gravitational field strength (N/kg)
Earth g = 10 N/kg
Mars g = 4 N/kg
Moon = 1.6 N/kg
If an object has a mass of 60kg on the Earth how much
does it weigh on each of the places shown above?
Weight on Earth =
Weight on Mars =
Weight on the Moon =
Falling objects
• Free fall – only weight acts on an object.
Acceleration = gravitational field strength.
• In a fluid drag increases as speed increases.
Velocity-time graph
Velocity, m/s
3.0
falling in air
2.5
2.0
1.5
Falling in liquid
1.0
0.5
0.0
0
0.05
0.10
0.15
0.20
0.25
Time, s
1. Why is there a difference in the 2 lines?
2. What is the terminal velocity in a liquid?
2_5 Falling objects
Summary
1. The weight of an object is the force
of gravity on it.
2. An object falling freely on Earth
accelerates at about 10m/s2.
3. An object falling in a fluid eventually
reaches its terminal velocity.
Mass and Weight
Weight (N) = mass (kg) x gravitational field strength (N/kg)
• Mass measures how much of something
there is. More mass makes it harder to
accelerate an object.
• Weight measures how much a mass is
attracted to another e.g. towards the
Earth.