Year 7 Science Forces - Homework 1Name: ______
Introduction to Forces – Forces around us 2018Form: ______Date Due: ______
Use the information given.
- What is a force?
______ - A force is being applied to an object. What 5 things might happen to it?
______
______
______ - The scientific term for Slowing down: ______and
Speeding up ______. - Give 2 examples of situations (other than those mentioned above) where an object:
Situation / Example _ describe briefly
Stops
Speeds up
Changes direction
Changes shape
Slowing down
Starts movement
- Look around your room / house, identify 4 forces that act through contact only.
______
______
______
______ - Which of the following are contact and non-contact forces?
Friction ______Magnetic force ______
Gravity ______Air resistance ______
Buoyancy ______Electrostatic force ______
Hitting a ball ______Swimming ______
- How to draw forces? What do you do to indicate a larger or small force?
______
______ - Name the equipment that is used to measure small force in the laboratory.
______ - How does this equipment work?
______
______ - What unit is used to measure forces? What is its symbol?
______ - Complete the labels of all the forces in the diagram - Push bike
Year 7 Science – Study of ForcesName: ______
A force = A push or a pull or a twist
What forces do:
A force is anything that changes motion. This meansthat a force can:
• get something going faster. In science we call thisacceleration. Your bike accelerates when you pedalit or when it rolls down a hill.
• stop something. Example: You stop moving whenyou fall off your bike.
• get something going slower (called deceleration).Example: You apply the brakes or go uphill.
• change the direction in which something istravelling. Example: You go around a corner.
• twist or change the shape of something. Sometimesthis change is permanent, but often the objectbounces back to its original shape. If this happens,we call it elastic.
Example: As they go overbumps, tyres squash and stretch but alwaysreturn to their original shape. If you fall, yourbones aren’t so elastic. They are unlikely to goback to their original shape, breaking or fracturinginstead.
Contact and non-contact forces
- Forces can be a push, pull or a twist.Most forces actually touch the object they are pushing or pulling around.
- Some forces, such asfriction, air resistance and buoyancy, are impossible to see but still make contact with the object that they areaffecting. These forces are called contact forces.
- Someforces, caused by gravity, magnetism and electricity,act through a ‘force-field’. These forces are invisibleand don’t actually touch the object that they arepushing or pulling around. These forces are callednon-contact forces.
How to draw forces
Scientists draw forces as arrows. The direction of thearrow is the same as the direction of the push or pull.Big forces are drawn as long arrows. A short arrowindicates a small force.
How to measure forces
A spring gets shorter when it is squashed bya push force, and gets longer when a pullforce stretches it. The bigger the force, themore the spring is squashed or stretched. These facts give us a way of measuring forces. The equipment is known as Newtonmeter or forcemeter or spring balance.
If apointer is attached to the spring and a scale is fixednearby, we can measure any change in the length ofthe spring. The spring balance and most kitchen andbathroom scales use this method to weigh things.
All forces are measured in Newtons,named after the famous English scientist,Sir Isaac Newton (1642–1727). Sometimesnewton is abbreviated as N. One kilogram isabout 10 N on the newton scale.Newton’s law of universal gravitation describes the gravitational attraction between bodies with mass, the earth and moon. He is very popular because of his 3 Laws of Motion.
Note: Mass is the amount of matter in an object or a person, it is the same everywhere in the universe. However, weight is a force acted on the object by gravity of the Earth and other space object. It varies on earth, moon and in space – Weightlessness!!!