A father lifts a toddler 1.5m into the air . The child gains 187.5 J of energy in her gravitational potential energy store as a result. What is the mass of the toddler (answer to 1dp) ( assume gravitational field strength is 10 N/kg)
Answers
Answer:
A gravitational attractive forces acts between all objects of any mass, no matter how close or far apart they are.
Gravity is universal and its non-contact force exists wherever there is mass.
All objects have a gravitational field around them.
Therefore, there is always a force of attraction between all objects all the time.
You experience gravity it as you jump up vertically against it's force and are then pulled back down to earth by the same force.
It was Isaac Newton who first realised that objects fell to Earth due to gravitational field attraction.
He not only recognised that gravity was a universal law of nature, but realised you could not only apply it to 'falling objects', but also to the motion of the planets around our Sun and our Moon orbiting the Earth.
BUT, remember, you are attracting the Earth at the same time as it attracts you. You don't notice this because your mass is so much smaller than the Earth. You only consciously experience yourself being attracted to the Earth.
Gravity makes everything fall towards the surface of an object e.g. like a planet, and it is gravity that gives everything 'weight' (explained below).
The force of gravitational attraction between two masses increases by two factors:
(i) The bigger the two masses involved
With its bigger mass, an elephant is more strongly attracted to the earth than you!
The greater a planet's mass, the greater the strength of the gravitational field around it.
(ii) The closer the two objects are together
The further you go above the Earth's surface the weaker the gravitational attraction between you and your planet.
Note: Although not needed for GCSE: F m1 x m2/d2,
F = force of attraction between the two objects, m = masses of the two attracted objects, d = distance from centres of gravity of the two objects
So you can relate this arithmetical proportionality equation to the two rules above)
You don't really notice gravitational attraction between objects around you because the gravitational fields are too weak. However, because the huge mass of the Earth and its very strong gravitational field, you definitely notice objects falling towards it. BUT, with gravity, we are always dealing with mutual attraction, so, what you don't notice is that your body is attracting the Earth towards it - think about it!