Forces: gravity, air & water resistance

Gravity, weight vs mass, friction, air resistance, water resistance, levers, and pulleys

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1
What force pulls objects toward the centre of the Earth? A) Gravity B) Friction C) Magnetism D) Air resistance
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2
Why does a parachute slow a skydiver down? A) It increases air resistance B) It reduces gravity C) It makes the person lighter D) It pushes the person upward
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3
Complete the sentence about friction. Friction is a force that acts between two surfaces that are ___ against each other, and it slows movement down.
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4
Which force pulls everything towards the Earth? A) Gravity B) Friction C) Magnetism D) Air resistance
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5
True or false? A feather and a bowling ball would fall at the same speed if there were no air resistance. A) True B) False
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6
True or false? Weight and mass are the same thing. A) True B) False
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7
Which shape would experience the least water resistance when moving through water? A) Streamlined (pointed) shape B) Flat square shape C) Cube shape D) Star shape
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8
Two children on a see-saw are balanced. Child A weighs 30 kg and sits 2 metres from the pivot. Child B weighs 20 kg. How far from the pivot must Child B sit? A) 3 metres B) 2 metres C) 1 metre D) 4 metres
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9
True or false? A pulley can change the direction of a force, allowing you to pull down to lift something up. A) True B) False
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10
True or false? Gravity on the Moon is weaker than on Earth, so things weigh less there. A) True B) False
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Answer key

Forces: gravity, air & water resistance · for parents and teachers

1
Gravity
Gravity is the force that pulls all objects with mass toward each other. On Earth, it pulls everything toward the centre of the planet.
2
It increases air resistance
A parachute has a large surface area that catches the air, increasing air resistance (drag). This force acts upward against gravity, slowing the fall.
3
rubbing
Friction occurs when two surfaces rub together. It opposes movement and produces heat. Rough surfaces create more friction than smooth ones.
4
Gravity
Gravity is a force that pulls objects towards the centre of the Earth.
5
True
In a vacuum (no air), all objects fall at the same rate regardless of mass. On Earth, the feather falls slowly because air resistance has a greater effect on its large, light surface.
6
False
Mass is the amount of matter in an object (measured in kg) and stays the same everywhere. Weight is the force of gravity acting on that mass (measured in Newtons) and changes depending on the strength of gravity.
7
Streamlined (pointed) shape
A streamlined shape allows water to flow smoothly around it, reducing water resistance (drag). Fish and submarines use this shape to move efficiently through water.
8
3 metres
For a balanced lever: force x distance is equal on both sides. 30 x 2 = 60, so 20 x distance = 60, meaning distance = 3 metres.
9
True
A single pulley changes the direction of force. You pull down on one end of the rope (using your weight to help), and the load goes up. This makes lifting feel easier.
10
True
True. The Moon has much less mass, so its gravity is weaker. Astronauts weigh less on the Moon.