Work and Machines
1. What is meant by:
a)doing work:- Using a force to move an object.
b)a machine:- a machine is anything that makes something easy to work with
2.Are you doing work when you are:
a)pushing a mower:- Yes, because when you're pushing the mower, you're using force.
b)cleaning your teeth:- No, because you're not using force to clean your teeth.
c))cycling:- Yes, because when you are pushing down the pedals, you're using force.
d)reading this page:- No, because you're not using force to read this page.
3.Why must you eat if you are going to keep working?
-You must eat if you want to keep working because food gives you energy and if you don't have a lot of energy, you're going to feel tired and maybe even faint.
4.Why are spanners, pilers, and can openers called machines?
-These are called machines because they make the work you do very easy and simpler.
5. Try to find out the names of some other simple machines:-
-Screw (eg.nail)
-Inclined Plane (eg. ladder)
-Wheel&Axle (eg.wheels for bicycles)
-Wedge
-Lever (eg.Hammers)
-Pulleys (ex.bags)
Pulleys, gears, and other wheels
1.What do you need to make a pulley steam?▲
- If you want to make a pulley system, you will need a set of pulley wheels and a rope.
2.Give two reasons why it is easier for a mechanic to lift a car engine out using a pulley system. ▲
-Its easier to lift a car engine out because the machine can pull it out very easily. It can't put it back in because it won't put it in the exact place with at the exact moment.
3. What is the job of:
a) the chain:- the chain turns the wheel and it transmits the force to the back of the wheel.
b) the gears on a bicycle:- the gears change the number of times that the crankshaft turns the wheels.
4. Turning a bicycle crankshaft turns on the back wheel. What is the difference between cycling in high hear and low gear?
-The difference between high gear and low gear is that in high gear, the chain runs over the small cog wheel at the back, but in low gear, the chain now has to run over the large cog wheel at the back.
5. Try to find out some other uses of pulleys:
-A pulley can change the direction of a pulling line.
Building a pyramid
1.Which simple machines were used ▲:
a) to split the blocks:- Wedges
b) to move the blocks:- Flat bottomed, barge like boats
c) to put the blocks in place:- Ramps
2.
a)How was friction reduced when the blocks were moved?▲
- The friction was reduced when the blocks were moved because they need to pull the block up the ramp which caused a lot of friction and they just had to put it in its place.
b) A simple invention, first used 700 years after the Pyramid was built, would have reduced friction further. What is it?
-The crane
3. Draw a diagram to show how to lift a block of stone using lever.
-
4. Wedge shaped tools and ramps are still in use. Give some examples of how they are used:
- They're used in construction sites to lift heavy objects like stones.
5. How much work had to be done to raise the last block(weighing 25,000 N) on to the top of the Pyramid?
- A lot of force had to be used to lift the last block to the top of the Pyramid.
-Al-Dana Al-Thani
Science 8D
Mr. Rhodes
22/02/2010
