Forces
Define ‘weight’.
a force due to gravity on an object
It is more slippery walking on ice than walking on a footpath. This is because”
there is less friction between the ice and your shoes
Identify will a north and south pole of a magnet attract or repel
The north and south pole will attract
If all forces of a car are balanced are you moving or stopped or both explain?
The driving force is equally matched by the opposing friction forces (wind resistance, road friction). The car is in motion, however neither accelerating nor decelerating. The car is travelling at the same constant speed.
Or the car is still so all forces balanced
List the order of effort load and fulcrum for a first-class lever
Effort, fulcrum, load
Identify two examples of contact forces
push and pull
What is friction and how does it increase?
Contact between two surfaces cause friction. Friction acts in the direction opposite to motion. The rougher the surface the greater the friction. Friction depends on; roughness of surface, hardness of surface and weight of the object.
identify areas with stronger magnetic fields and areas of weaker magnetic fields around the magnet.
The closer the magnetic field lines are the stronger the magnetitic pull is
Explain what is meant by the term inertia.
The tendency for an object to remain at rest until any external force acts upon it.
List the order for a second-class lever and give an example
Fulcrum, load, effort
wheelbarrow
If a boat is sinking explain what is happening in terms of forces
The weight of the ship is larger than the buoyancy
Your car engine gets hot as the car is driven. Is this friction helpful or a nuisance?
You apply the brakes on your bike when you see a child on the road ahead. Helpful or nuisance?
Nuisance
Helpful
If you weighed 500 N on earth and the gravity on neptune is 1.5 stronger what weight would you be?
750N
If a car is driving with a force of 1500 N and the air resistance is 200N and friction of the road is 100N what is the net force?
1200N driving force
The arm is what class lever and what order is it in?
Third class lever
load, effort fulcrum
A car is moving forward at a constant speed. All forces acting on the car are equal in size. How would you accelerate and decelerate (explain in terms of forces)
Accelerate-Driving force would need to increase or friction decrease
Decelerate-Friction force would need t0 increase or driving force decrease
What is the difference between a contact and non contact force and give examples
Contact forces are touching and non-contact forces and not touching eg gravity-non contact, contact force is pushing someone down a slide
How can you create a magnet with a nail, explain in terms of domains
By stroking a nail in the same direction with a magnet the domains will all line up in the same direction causing it to become magnetised
When a parachute opens up what are the forces acting on the person
Air resistance upwards
weight due to gravity downwards
You have a lever positioned underneath a heavy rock that you are trying to shift. Where is the best place to put the fulcrum in order to lift the heavy rock with the least effort.
Closer to the load.The closer the fulcrum is to the load, the greater the multiplied force acting on the load.
On the Moon, a stone and a feather dropped together will hit the ground at the same time. When this experiment is repeated on Earth, the stone hits the ground first.
Explain why this happens.
Gravity acts equally on both objects on earth. However, the earth’s atmosphere causes the feather to fall slower
due to the larger surface area of the feather and the air resistance acting on the larger area.
There is no atmosphere/air on the moon to act as resistance on either object.
List 3 ways to reduce friction
Lubrication
Smoother surfaces
Use of air or magnetic repel
The further you go into space from earth what happens to the magnetic field and where would the magnetic field be the greatest on earth
The magnetic field decreases.
The magnetic field increases at the North and South Poles
Explain the effect of a shorter forearm [elbow to wrist distance] on the ability of an athlete to lift heavy weights?
If the fulcrum is positioned close to the load, a heavier load can be lifted with the same amount of force.
The athlete with a shorter forearm should find lifting weights easier than if their forearm was larger.
If a smaller axle and larger axle are rotated, identify whether which gear will turn faster and what is the speed multiplier the small or large gear. Explain your decision
The small gear will turn faster
The larger gear acts as a speed multiplier
The larger gear is the driving gear