Forces and Motion Flashcards
Calculate speed from raw data by dividing the
total distance travelled by the total time taken
If a car travels 150 km in 3 hours, what is its speed?
Speed = Total distance ÷ Total time
= 150 km ÷ 3 hours = 50 km/h.
Convert 15 m/s into km/h
54 km/h
Convert 9 m/s to km/h
32.4 km/h
Convert 100km/h to m/s
27.7 m/s
Convery 53m/s to km/h
190.8 km/h
What is speed defined as?
Distance travelled over a period of time.
What unit do u use for speed?
m/s
How do you convert 20 m/s to km/h?
20m/s × 3.6=72km/h
What is the conversion from meters to kilometers?
1 km = 1000 m
How many seconds are in an hour?
1 hour = 3600 seconds
What is 3600 ÷1000?
3600/1000=3.6
What do the DST triangles look like?
D on the top, S on the left, T on the right
Matilda walks 2000m in 50 minutes. What is her speed in m/s?
0.67 m/s
James tries to walk the same distance at a speed of 5m/s. How long does he take? 2000m is the distance
400s
What are 2 different common units for speed?
meters per second (m/s)
kilometers per hour (km/h)
How far is 250m in Kilometers?
0.25km
How to calculate the acceleration,
change in speed (m/s) /time taken (s)
Acceleration
Process where the velocity changes.
A cyclist accelerates from 0 to 10m/s in 5 seconds. What is her acceleration?
2 m/s2
A ball is dropped and accelerates downwards at a rate of 10m/s2 for 5 seconds. How fast will it be going?
50 m/s
What is a Force??
A push or a pull or a twist
What are 3 Non-Contact Forces?
Gravitational forces
Electrostatic forces
Magnetic forces
What are 3 Contact Forces?
Friction
Supporting structures
Air and water resistance
What is Newton’s Third Law of Motion?
Every force causes an =
equal and opposite force
How do we define a Resultant Force?
A single force that can replace all the other forces acting on something
How do we measure force?
We measure force using a “force meter”
Force meters contain a spring connected to a metal hook. The spring stretches when a force is applied to the hook. The bigger the force applied, the longer the spring stretches and the bigger the reading.
Force is measured in Newtons (N)
1kg mass weighs 10N on Earth
The gravity force on earth is actually 9.8 N - but we round this to 10 N
What is Newtons 1st Law of Motion?
Basically, an object will remain at rest or continue to move with constant speed as long as the forces acting on it are balanced.
What does the weight triangle look like?
w (weight) at the top, M (mass) on the left, g (gravitational field strength) on the right
What is the weight on Earth of a book with mass 2kg?
20N
What is the weight on Earth of an apple with mass 100g?
1N
What is Newton’s 2nd Law of Motion
A force (push or pull) = Mass x Aceeleration
What does the Force Triangle look like
F (force) on the top, M (mass) on the left, A (acceleration) on the right)
If I throw a 500g basketball with a force of 10N, what is its acceleration?
- Convert mass: 500 g = 0.5 kg
- Calculate acceleration: a = F/m = 10 N / 0.5 kg = 20 m/s²
Name three types of potential energy
1) Gravitational potential energy 2) Elastic potential energy 3) Chemical potential energy
Name three types of active forms of energy
1) Kinetic energy 2) Thermal energy 3) Electrical energy
Name the energy changes for a person dropping a ball
Gravitational potential energy to kinetic energy
What is the law of conservation of energy
Energy comes in different forms
Energy cannot be created or destroyed
Energy can be changed into other forms of energy
What is energy defined as?
Energy is required to do work – making things move
or change.
* Energy isn’t a substance but it is in everything.
* Energy cannot be made or destroyed.
What is Energy measured in?
Energy is measured in Joules (J) or kilojoules (kJ)
How is energy change in a object associated with work?
Work is the amount of energy used to move an object
What does the ‘Work Done’ triangle look like?
W (work done) at the top, F (force) on the left, and D (Distance moved) on the right
If we pushed a car along a flat road for 50m with a
force of 200N, how much work is done?
W = F x d = 200 x 50 = 10000J
If I lifted a 2kg mass from the ground to the top of
my head (1.58m), what work has been done on
the mass?
Force = gravity = 10N per kg
W = 20 x 1.58 = 31.6J
Amy pushes a book 5m along the table with a force of 5N. She gets tired and decides to call it a day. How much work did she do?
25J
What is the unit for work?
Joules (J)
What is 230kg in Newtons on earth?
Weight (N) = mass (kg) × gravitational acceleration (9.8 m/s²)
= 230 kg × 9.8 m/s² = 2254 N
What is the difference between Mass and Weight?
Mass is the amount of matter in an object (measured in kg), while weight is the force exerted by gravity on that mass (measured in Newtons).
What is Power?
Power is the rate at which work is done.
What does the Power Triangle look like?
W (work done) at the top, P (power) on the left, T (time) on the right
Jude runs up the stairs. She is lifting her bodyweight up.
1) Her body has a mass of 60kg, calculate her weight.
2) The staircase is 20 m high. When she lifts up her body weight, how much work is she doing?
3) She runs up in 5 seconds. How much power does she have?
4) His friend James (also 60kg) can run up a 30 m staircase in the same time. Does he have more or less power? Compare numbers.
1) 600N
2) 12000J
3) 2400W
4) 3600W
