Revision Year 7 Flashcards
(23 cards)
What is at the centre of the Solar System?
The sun.
Why did people years ago think that the Earth was the centre of the solar system?
They were living on earth and saw the moon and sun going round the earth and so they thought they were the centre of the universe.
Why do we have day and night?
We have day and night because the earth takes 24 hours to rotate around it’s own axis and half that time half the earth is in the shade from the sun, (night) and the other half it’s in the light (day)
What makes a day have 24 hours?
Because that’s how long it takes for the earth to rotate on it’s it’s own axis
What makes a year 365 days long?
That’s how long it takes the earth to rotate round the sun.
Name a planet with a longer year than the earth
Jupiter
Neptune
Why are the stars in May different to the stars we see in December?
we see different parts of the sky at different points in the year.
What three things about an object can a force change?
Shape, size and direction
Going to the moon would change one, which one, weight or mass.? And why?
Weight, because mass never changes.
What is Newton’s 1st law of motion?
An object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless an unbalanced force is applied to it.
What are the three forces acting in this room, and one that doesn’t.
Gravity, friction, air resistance and one that isn’t is water resistance.
A box has a 5n force acting on it pushing it to the left and a 4n force acting on it pushing it to the right. Calculate the resultant force.
1n to the left
The forces on the boxes are moved ,now both forces act downwards. What is the resultant force
9n downwards
Why are racing cars flat and smooth?
The lower the vehicle the less air resistance it will encounter. Air resistance will slow it down. The smother the vehicle the easier it is for air to travel over it.
If I want to reflect infra-red radiation when I go outside, what colour should my coat be?
White because if infra-red bounces of it.
Removing the air from inside something creates a vacuum. Why is this hard to do in a lab?
Because there oxygen in a lab and it’s hard to remove from something.
what is the earth’s gravitational field strength?
10n/Kg
On earth what does a mass of 12kg weigh?
120kg
On Jupiter, where g=22N/kg, what does the same mass weigh?
264 kg
What causes pressure on your goggles when you go underwater?
Liquids exert pressure on objects. The pressure changes with depth. The pressure of water presses on your goggles, which pushes your goggles onto your face. The deeper you go the greater the force pushing on your goggles.
If I put an object on a Newtonmeter and get a reading of 32N, did I measure weight or mass.
Weight
What is the mass of an object with weight 4.5N on earth?
450g
Where would I go if I wanted to be weightless and why?
You can be weightless in an aircraft — space has nothing to do with it other than the duration of the weightless period. In a zero-G unload a jet aircraft can sustain weightlessness for 30 sec or more.
