Physics Unit 3- Mechanics Revision

1. Objects move at a steady speed in a straight line unless ?

2. Movement in circle requires a ? force to be constantly acting on the object.

3. The size of force needed is more if which 3 things happen?

4. In a swing or pendulum, ? in the string provides this force

5. In an orbit, ? provides the centripetal force.

6. In an atom, electrons are attracted to the nucleas by a centripetal force, which is ?

7. Although the speed in a circular orbit stays constant, the velocity doesn't. Why?

1. There is an unbalanced force acting upon them.

2. Centripetal force.

3. The mass increases, the speed increases or the radius decreases.

4. Tension.

5. Gravity.

6. Electrostatic forces.

7. Because the direction is constantly changing, therefore the object is accelerating.

1. The Universe is a collection of a huge number of ?

2. Galaxies are collections of billions of ?

3. Stars (like our Sun) form from ?

4. Stars generate energy by ? reactions.

5. A huge amount of ? is released in each reaction so stars shine for billions of years.

6. In a star's Main Sequence or Stable Period, how does the star stay at a constant size in terms of forces?

1. Galaxies

2. Stars

3. Nebulae (clouds of gas and dust)

4. Nuclear Fusion

5. Energy

6. The outward pressure of radiation balances the inward pull of gravity.

1.Stars up to 1.5 times the size of our Sun form from a ?

2. As they run out of ?, they use heavier elements such as ? in their reactions.

3. They expand to become ?

4. As they cool they become ?

1. Stellar Nursery

2. Hydrogen, Helium

3. Red Giants

4. White Dwarfs

1. Huge stars are 1.5 to 3 times the mass of our Sun. The form from collapsing clouds of interstellar gas and dust known as ?

2. Giant stars are over ? times the mass of our Sun.

3. Following their Main sequence or Stable period, both expand to become ?

4. They then explode into a ?

5. They then leave behind a ? or a ?

6. The material from exploding stars includes elements other than hydrogen, which are then ?

1. Nebulae

2. 3

3. Red Supergiants

4. Supernova

5. Neutron Star, Black Hole

6. Recycled to make new stars and planets