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KS3 Forces Motion
KS3 Forces and effect on movement
Question | Answer |
---|---|
What is a force ? | a force is a push or pull movement |
What unit measures force? | newtons |
name contact forces | friction, upthrust, air resistance |
name non-contact forces | gravity, magnetic field |
Define upthrust | upthrust is the upward force that a liquid or gas use on a body floating in it. |
Define gravity | is the force that attracts a body towards the centre of the earth |
what is friction? | friction is a force that slows you down, created when one object rubs against another! |
what is air resistance? | air resistance is the opposite force to movement and air resistance is created by particles! |
Explain why air resistance increases when you move faster? | more particles |
Which force pulls you down when sky-diving? | gravity |
Which force slows you down while sky-diving? | air resistance |
When you drive in a car, which force hits against a car? | air resistance |
Where does upthrust occur? | in water |
Which force keeps us on the ground so we don’t float away? | gravity. |
In which direction does gravitational force apply | downwards |
Suggest what would happen to the weight and to the mass of an astronaut who travelled to space | the weight will be the different because only the mass does not change but when you are in space your weight changes it becomes lighter. |
Describe and explain what happens to air resistance as you move faster | air resistance increases as there are more particles to hit you |
Why do dolphins have a streamlined shape | it enable them to move through water with the least possible water resistance. |
What happens to the air resistance when the parachute is opened | when the parachute opens the air resistance will become much greater which slows the person riding it |
What happens to the forces on a skydiver when the parachute opened for a few seconds | As his speed reduces the air resistance will become less and eventually the forces will be the same again. |
When you jump out of a plane and you open your parachute, describe the forces on you and your speed after a few minutes opening it? | forces (air resistance and gravity) are balanced and you are moving at a constant speed. |
Explain the difference between mass and weight | Weight is the force that pulls you down; mass is the Number of atoms in the body |
What will be different on the moon than on the earth: mass or weight? | The weight! The mass measures the number of atoms in a body. That will NOT change on the Moon: you stay the same mass! |
What is the force that keeps you afloat in water? | Upthrust |
What can you do to make a car go faster? | Streamlining |
Forces can make things change shape, speed or direction true or false | True |
When are forces balanced? | Forces are balanced when they are equal in SIZE but opposite in DIRECTION: the forces cancel each other out. |
When are forces unbalanced? | Forces are unbalanced when two forces are opposite in DIRECTION and one has a bigger SIZE than the other |
Which of either the moon or the earth has more gravity? | The Earth |
fill in the blank: if the forces on an object are balanced and the object is ............., then it will remain stationary | answer is stationary |
What is the effect of unbalanced forces on a moving object? | direction may change, or the object may slow down, or it may accelerate(go faster) |
This person is pushing down on the chair with force of 650N. What other force is acting to make it balanced | Reaction of the floor |
In a tug of war, when one team is pulling with a force of 100 N to the left and the other 80 N to the right, what is the net force? | Answer: 20N to the left |
A car is moving at a constant speed and the thrust of the engine is 500N forward. How big is the friction? | because the car is moving at a constant speed, it means that the forces are balanced. So friction is 500N backwards. |
A car is moving faster (accelerating) and the thrust of the engine is 700N forward. How big is the friction? | because the car is moving FASTER, it means that the forces are UNbalanced. So friction is less than 700N backwards. |
A car is slowing down (decelerating). Compare the SIZE of thrust of the engine and friction | because the car is moving SLOWER, it means that the forces are UNbalanced. As the car is slowing down, it means that the backwards force is bigger: so friction is more than the thrust of the engine. |
What are the 4 forces on a car moving at a steady/constant speed | Gravity, Push of the floor, Thrust of engine, Air resistance/friction |
Compare the size of the 4 forces on a car moving at a STEADY/CONSTANT speed | Gravity is the same size as Push of the floor. Thrust of engine, is the same size as Air resistance/friction |
What are the 2 forces on a stationary car | Gravity, Push of the floor |
Compare the SIZE of the 2 forces on a stationary car | Gravity and Push of the floor are the same SIZE |