Flashcards
9 Space Travel
Cards in this deck (12)
- 19 . 1 When we apply a force on an object , what will happens to the object ?1 ) Change the speed of the object
2 ) Change the direction in which
the object moves
3 ) Change the shape of an object - 2There are two kinds of forces , states them.1 ) Contact force : When one object applies a force on another object through direct object .
2 ) Non-contact force : An object apply a force on another object
that is not in direct contact - 3Gives some example of the two kinds of force .1 ) Contact force : Push / pull the doors
2 ) Non-contact force : Force of gravity / magnetic force - 4In the laboratory , How can we measure the forces ?We can measure forces by a newton balance or spring balance .
The unit of force is the newton ( N ). - 59 . 2 What is friction ?Whatever an object slides over or tends to slide over another object , a force arises to oppose this change . It is friction . It is a contact force .Friction always oppose the motion or the tendency of motion of an object.
- 6What is air resistance ?When an object moves through air or water , there are opposing force acting on an object by air . It is called the air resistance .
- 7Briefly explain the heating effect of friction .When an object moves against friction , kinetic energy changes to heat energy.
- 8Why we need to reduce the friction ?1 ) Since the friction opposes the motion of an object , it can slow down and even stop the object.
2 ) The object wears out as it moves against friction .
3 ) The kinetic energy of the object is changed to heat energy , which is often unnecessary and leads to a waste of energy . - 9How can we reduce the friction ?1 ) Using rolling beads
2 ) Supporting the object on an air cushion
3 ) Adding lubricant between the object and the surface .
4 ) Streamlining an object - 109 . 3 What is the force of gravity ?The Earth pulls an object towards its centre even when it is not direct contact with the object. This is called the force of gravity .it is a non-contact force .
- 11What is mass ?1 ) Mass shows the amount of matter in the object .
2 ) It can be measured in kilogram ( kg ) or gram ( g ).
3 ) For a certain object , its matter is the same in all places , nits mass is also the same in all place . - 12What is weight ?1 ) weight id the Earth's force gravity acting on an object
2 ) It can be measured in newton ( N )
3 ) For a certain object , weight can different in different locations , where the force of gravity is different .
Information
- Description
- Flashcards on 9 Space Travel, created by Yeung Kam Fan on 09/04/2016.
- Created by
- Yeung Kam Fan
- Views
- 12
- Tags
- Rating