Year 8 Science - Forces

Flashcards about forces for Year 8 Science review.

What is a Contact Force?

A force which only occurs when objects actually touch one another

What is a Non-Contact Force?

A force which acts at a distance without objects touching (e.g., gravity, magnetism)

What is an Electromagnet?

A magnet which is turned on and off by electricity

What is Weight?

A measure of the force of gravity on an object

What is Gravity?

A non-contact force which attracts objects to each other

What is a Spring balance?

A piece of equipment used to measure forces

What is Friction?

A type of force which opposes motion

What is Magnetic?

An object which is attracted by a magnet

What is Force?

Something that can change motion, a push, pull or twist

What is Mass?

The amount of matter in an object

What is Magnetic Field?

The area surrounding a magnet in which a magnetic object will experience a force

What is Newton?

The units used to measure force (N)

What is Attract?

When objects are pulled together

What is Repel?

When objects are pushed away from each other

What is Unbalanced?

When opposing forces are a different size

What is Balanced?

When opposing forces are the same size

What is Acceleration?

When the speed of an object increases

What is a Crumple Zone?

A part of a vehicle designed to absorb energy during a collision, reducing the impact on passengers

What is a Van de Graaff generator?

A machine that generates static electricity by building up electric charge on a metal dome

What is a force?

A force is a push, a pull or a twist that can change the speed, direction, or shape of an object.

What are contact and non-contact forces?

Contact forces occur when two objects come into direct contact, such as normal force, applied force, and friction. Non-contact forces occur even when objects are not touching, such as gravity, magnetic forces, and electrostatic forces.

What is needed to start an object moving and what forces can act from a distance?

A force is needed to start an object moving and can change an object's direction, speed, and shape. Gravity, magnetism, and electrostatic forces can act from a distance.

What is a Newton and what is used to measure force?

A Newton (N) is the unit of force in the International System of Units (SI), measuring how much force is needed to move a 1 kilogram object by 1 meter per second squared. Forces are measured using a spring balance.

What are balanced and unbalanced forces?

Balanced forces are equal in size and opposite in direction, resulting in no change in motion. Unbalanced forces are not equal, causing a change in motion.

What is Net Force?

Net force (or Resultant Force) is the total force acting on an object after all forces are added together.

In the skydiving example, what is the resistive force acting against Dennis before his parachute opens, and what is its magnitude?

The resistive force acting against Dennis is Air resistance and its magnitude is 750N.

What does friction do?

Friction slows down movement. Small bumps on rough surfaces catch, and friction acts between materials in contact, creating heat. It can be helpful (walking) or a nuisance (engine overheating).

What feature of a surface seems to determine the amount of friction?

The amount of friction depends on the surface, with rougher surfaces producing more friction than smooth surfaces.

What is friction?

Friction is a force caused by two surfaces moving over each other. Rough surfaces produce more friction than smooth surfaces.

What is Lubrication?

Oil on bike parts reduces friction, making it work better. Without oil on the wheel rim the brake blocks wouldn't work. Forces the girl is pushing against while going uphill are gravity and friction. Forces slowing down bike C are friction and air resistance. As bike D goes through the puddle, friction will increase and lubrication will decrease. Washing up liquid helps remove the ring by acting as a lubricant.

How do shoes reduce forces on your feet and crumple zones absorb some impact in car accidents?

The design of shoe soles provide grip and reduce impact force. When you step on a rock, the sole deforms around the rock, spreading the contact force over a larger area. In car accidents, the crumple zone deforms and reduces forces on the driver and passengers.

In a car crash, what happens to kinetic energy and how are passengers injured?

Kinetic energy is converted into other forms of energy, crushing and deforming the car. Passengers can be injured by being thrown forward due to inertia.

Why do car accidents become more likely as speed increases?

Stopping distance increases with speed due to reaction time and braking distance. Kinetic energy increases with the square of velocity, so the severity of accidents increases with speed.

What features reduce injury to road users in a crash?

Head Rests, Crumple Zones, Seat Belts, Airbags, Side-Impact Protection System ,and Pedestrian Friendly Bonnet Design.

What are Crash Avoidance Features?

Crash avoidance features include Anti-lock Brake System (ABS), Blind Spot Warnings, Lane-Keep Assist, Active Cruise Control, Electronic Stability Control (ESC), Driver Fatigue Monitoring, Auto Emergency Braking (AEB) and Intelligent Speed Adaptation (ISA).

What is gravity?

Gravitational forces hold the moon in orbit around the Earth and the Earth in orbit around the sun. Mass measures how much matter a substance contains and does not change with location. Weight is a measure of the force of the gravitational force acting on you.

Why do objects appear lighter in water?

Gravity pulls all objects towards the Earth, giving us weight. The stone felt lighter when it was under water because upthrust was pushing it up. Forces: gravity and upthrust.

How to Calculate Weight Force?

To calculate weight force: Force (w) = mass of your body X 9.8

What is the relationship between gravitational field strength and weight on Earth compared to the Moon?

The gravitational field strength on Earth is greater than the gravitational field strength on the Moon. If an astronaut traveled to the Moon, their weight would be smaller than their weight on Earth.

Why do bigger parachutes fall slower?

Bigger parachutes fall slower than small ones because they have more air resistance than smaller ones, due to a bigger area.

How do objects become charged?

Objects become charged by the addition or removal of electrons, resulting in an electrostatic charge. Rubbing a neutral material against another can add or remove electrons.

How does static electricity with subatomic particles work?

When two insulating materials come into contact, electrons can transfer. The object which gains electrons becomes negatively charged, and the object which loses them becomes positively charged. Oppositely charged objects attract, while same charged objects repel.

What charge makes objects repel?

Objects with the same charge repel each other.

What items do magnets attract?

Magnets attract iron, steel, and other magnetic materials but not wood, plastic, aluminium, copper, or paper.

What is a magnetic field?

A magnetic field is the space around a magnet where it can affect magnetic materials. You can use iron filings to find the shape of a magnetic field. A compass will point towards the north pole of the magnet.

What is the correct description a permanent magnet?

A material that remains magnetic for a long time after the magnetising force has been removed.

What factors affect the strength of your electromagnet?

Increasing the number of turns of wire around a nail or increasing the voltage supply affects the strength of the electromagnet.

What is lodestone or magnetite?

Hundreds of years ago, the Greeks knew about a rock that attracted iron. They called it lodestone or magnetite. Sir William Gilbert, the private doctor of Queen Elizabeth I of England, first explained the Earth's magnetic field.

What is force?

Forces can be a push, a twist, a or a pull. The two poles of a magnet are north and south.