Mariah (7) asks “Why are pushes and pulls forces?”

Thanks team and thanks Mariah for the question.  My team are quite correct there are lots of pushes and pulls. Can you think of more? What about gravity? That pulls things to the ground. What about the wind, that pushes things.

In science and in our daily life we put things into groups. The things in the group all have something in common. All fish are grouped together, they can all breathe underwater. Can you see anything else they have in all fish have which is the same?
All bicycles are grouped together, they all have two wheels. They also have some other things in common (the same).

If all forces are grouped together , they all involve pushes and pulls. The group that pushes and pulls is called forces.

“If I was sucked into a black hole what would make me die?” asked James (12)

James, thank you for your question. I had a similar question from  Sheereen  click here to see my, and my friends answer.

It is thought that a ‘black hole’ is produced when a rather large star comes to the end of it’s life. It collapses in on itself and forms an object of incredibly concentrated matter. As ‘gravity’ is a property of the quantity of matter (see my answer to Ernie’s question) the collapse causes an immense increase in the gravity from the  smaller collapsed star.  

It is unlikely that our Sun would end in this way as it is classified as a smallish star. It is likely to become something called a ‘Red Dwarf’ star.

The ‘black hole’ is explained by the fact that this concentration of gravity ‘pulls’ light into it, thus the ‘hole’.

Now if you were close to the collapsed star in your spaceship you would also be pulled into it and unfortunately be added to the mass of the collapsed star. Sorry, you will be crushed.

(slightly revised 20/4/2016)

“If I do a headstand will my brain get too much blood?” asks Susan (8)

Susan , I asked my friends about your question and this was their thoughts.

Thanks team, some interesting thoughts. Firstly let’s confirm that it is the heart that pumps the blood around our bodies. In a normal situation the heart is strong enough to pump the blood up to our head, so it might find it easier to pump the blood to our head when we are upside down. Any idea why? Think of gravity.

When you are doing a headstand the heart will not need to fight gravity to get the blood to your head, so it might find it a bit easier. It does however still need to get the blood to your feet (which are now above your heart) but it is strong enough to do this.

There might be some visible signs in the way the blood circulation changes. If blood has a little difficulty getting to the feet they might go a little pale. If the blood does not leave the head as quickly as usual, the face might go a little red. You might also get a change in the pulse rate if the heart has to work harder. These can all be tested with a healthy volunteer.

(edited 19/01/2017)

Ernie(13) asks -“What is at the centre of a black hole? What would happen if you fell into one?”


We obviously know something about gravity. We know that it is a force that is generated by the mass of an object. The bigger the mass the bigger the force that it exerts on other objects. So we feel the force of Earth’s gravity on us and the Earth feels the force of the  Sun’s gravity on it. The Sun’s gravitational force keeps the Earth on an orbit around it. If it didn’t exist the Earth and all the other planets would start wandering in space.

Black holes are thought to be a source of a massive gravitational force, because of their mass , which is constantly increasing, and they don’t just pull other matter to them they pull light in as well …thus a black hole. No light – darkness.

So to your question.  I think you could now answer that yourself.

“Can u jump off the world into space” was Austins question.

A great question Austin however I think you are going to be a little bit disappointed by my friends answers.

falling to earth

What a way to hand over to me!

To think about gravity you have to think about the really big things. the gravity of the Earth pulls on the Moon and keeps it in orbit. The gravity of the Moon pulls on the Earth and causes the tides. So gravity doesn’t end when you leave the Earth. Austin, jump and you will fall a long, long way.


Those astronauts are falling all the time but because they are moving around the Earth the ground is constantly moving away from them. If there spaceship stopped moving around the Earth it will fall and hit the ground. (revised 10/09/16 -miscalculation 13/09/16 new animated gif)

Charlotte asks the question “How does gravity hold you to the ground?”

Charlotte I can honestly say that I have no idea how gravity holds things down. I have asked my friends and await an answer.


Charlotte, my team seem to agree with me. In the 17th Century Newton and another scientist called Hooke did some great observations and experiments on falling objects and proposed that gravity was an attraction between any two masses AND the attraction was dependant on the size of the masses involved. For example you are attracted by the Earth and the Earth is attracted by you BUT your attraction is so much smaller than that of the Earth it does not affect the motion of the Earth. The attraction between you and the Earth is also dependant upon how far away you are from the Earth. The Moon is attracted by the Earth and the Earth is attracted by the Moon. They are both big bodies so gravity does affect the way they move with respect to each other and this dictates how the Moon orbits the Earth.

Some scientists including Einstein have put forward ideas on how gravity operates but even these are being challenged. There a lots of things which are still unanswered. The question just has to be asked.

Charlotte, the Earth’s circumference can be calculated by multiplying the diameter of the Earth by pi.(π)

Jessica (8) asks – How do the planets orbit the Sun? How many moons does Mars have?

Jessica. A great question. You also asked a question about the Moons of Mars so I will try to answer them both here. Firstly I asked my friends about the orbits of the planets.

Sometimes I think they tackle the easy bits and give me the hard bits.

Lets look at what we mean by a force. A force is a push or pull on something that you are interacting with. You are applying a force on somebody when you push them away or you are applying a force on something when you pull them to you. When you let go of them the force ends. When you are throwing a ball you are only applying a force in the throwing process. When you let go of the ball the force that you were applying ends.

Simple, but

Some of the forces can be applied without touching the thing you are forcing. Magnetism is an example one magnet will apply a force to another magnet without touching and  Newton realised that when objects fall towards the ground they fall because the Earth is applying a force on those objects. He called that force Gravity.

Now what is happening to the planets. Here is a little experiment. Tie a ball to a piece of string (a polystyrene ball would be the best). Now holding the end of the string spin the ball around your head (probably best to do this in the garden). Can you feel the tug(force) being applied on your hand. Now let it go. What happens? Does it just drop to the ground. Now think about this. The ball is a planet and your hand is the Sun. Not only gravity but another force linked to the speed of the flying ball and it’s mass is in action. Maybe it is the application of these two forces that make planets orbit the Sun?

Sorry long answer. Please comment if you want to by going to the Leave a Reply Button ….guidelines are available.

Mars has two small moons Phobos and Deimos.

A video that may help –