Forces- P5 - Paper 2 Flashcards
Vectors
Magnitude + direction
-force, velocity, displacement, acceleration, momentum
Scalar
Only magnitude and no direction
Distance
What is a contact force? (Name 4)
When 2 objects have to be touching for a force to act.
Friction, air resistance, tension in ropes, normal contact force.
What is mass? (2 points)
The amount of ‘stuff’ in an object. Every objects mass is the same everywhere in the universe
What is weight? (2 marks)
The force acting on an object due to gravity. Weight of an object depends on the strength on the gravitational field strength.
What is the equation for weight? (With units)
Weight (N) = Mass (kg) x Gravitational Field Strength (N/kg)
Which of these are vector and which are scalar:
-force
-speed
-distance
-velocity
-displacement
Vectors:
-force
-velocity
-displacement
Scalar:
-speed
-distance
3 contact forces:
Friction
Air resistance
Tension
3 non-contact forces:
Magnetic
Gravitational
Electrostatic
What can you use to measure an objects weight?
A newton meter
What is the equation that can be used to determine an objects weight?
Weight (N)= mass (kg) x Gravitational field strength (N/kg)
Calculate the weight of an object on the moon if its mass is 3kg. The gravitational field strength of the moon is 1.6N/kg.
W=MxGFS
W=3x1.6
W=4.8
Calculate the weight of an object on the moon if its mass is 3kg. The gravitational field strength of the moon is 1.6N/kg.
W=MxGFS
W=3x1.6
W=4.8
What is the effect on an object’s weight if its mass was doubled?
The weight is also doubled.
1000N
^
^
600N < van»_space; 800N
v
v
1000N
Calculate the resultant forces acting on the van above: horizontal and vertical.
Horizontal force: 200N to the right
Vertical force: Equilibrium/ 0N
1000N
^
^
600N < van»_space; 800N
v
v
1000N
On the diagram, what 2 things do the arrows show?
- Direction of force
- Relative size
Complete the sentences below:
Elastic deformation occurs when a force has been applied to a spring and it …………….. to its original shape. …………. …………….. occurs when the spring does not return to its original shape.
- Returns
- Inelastic deformation
State the equation that links force, spring constant and extension.
Force = spring constant x extension
Define work done.
This occurs when a force moves an object for a distance.
State the equation that links work done, force and distance.
Work done= force x distance
Units for work done, force, distance.
Work done, Joules (J)
Force, Newtons (N)
Distance, meters (M)
A lorry travels 200m when the brakes are applied with a force of 600N. Calculate the work done to stop the lorry.
Wd= fxd
Wd=600x200
Wd=120,000J
State 3 factors that could affect a person’s walking speed.
- Age
- Fitness
- Terrain
A car increases its velocity from 5m/s to 12m/s in a time of 10 seconds. Calculate its acceleration. (Units)
Acceleration= change in velocity/time
A=(12-5)/10
A=7/10
A=0.7m/s2
Explain the term deceleration.
Negative acceleration, the speed going down.
What is the calculation for stopping distance.
Stopping distance= thinking distance + breaking distance
What affects thinking distance?
Speed
Tiredness
Reaction time
Drugs
Alcohol
Distractions
What affects braking distance?
Tyres
Road conditions
Brake conditions
Let the mass of a car be 1500kg. One car is travelling at a speed of 20m/s and a second car is travelling at 15m/s. Calculate the force exerted if they were to hit an object.
Force = mass x acceleration
Car 1
1500 x 20
30,000N
Car2
1500 x 15
22,500N
Describe the effect of friction on a moving object.
It slows it down
State 2 ways friction can be overcome.
- using lubricant
- smoother surface
What is terminal velocity?
When an object is falling at a steady speed. Frictional force is equal to acceleration force so reaches maximum speed.
Terminal velocity depends on 2 things:
Shape
Area
Explain the term conservation of momentum.
The total momentum before an event is the same as after the event.
State the equation and the units to calculate momentum.
Momentum (kg m/s) = mass (kg) x velocity (m/s)
A car has a mass of 1500kg and a momentum of 7500kgm/s. Calculate its velocity.
Velocity = momentum/ mass
V= 7500/ 1500
V= 5m/s
State the equation that links force, mass and acceleration.
Force= mass x acceleration
Calculate the force acting on an object with a mass of 15kg and acceleration of 4m/s2.
F=mxa
F= 15 x 4
F= 60N
When an object moves in a circular motion, explain what happens to its direction and velocity if its speed remains constant.
Its direction and velocity will be constantly changing.
