Gravity, weight and
forces in buildings
3M
1. Fill in the missing words in the following passage using the selection given below.
Earth
weight
force
attraction
masses
gravity
Jupiter
more
field gravitational
centre
less
Gravity is the force of ______________ between things that have mass.
The _________ has a lot of mass and so it has a strong gravitational
_________ (region in which the Earth’s gravity can be felt). The Earth’s ______________ field attracts all the
___________ in the field towards the ____________ of the Earth, and it keeps the Moon in orbit round the
Earth. The _______________ of an object is the force with which gravity pulls on an object. The
_____________ mass an object has, the greater its weight. The unit of weight is the same as the unit of
_______________ the newton (N). The equation for calculating weight is:
Weight (N) = mass (kg) x acceleration due to gravity (m/s2). The stronger the gravitational field, the greater
the acceleration due to ____________. This is why the same object weighs ________ on the Moon and
more on ______________. Jupiter has much more mass than the Earth and the Moon has much less.
2. Because gravity acts to attract all masses towards the ground, buildings need to be carefully designed so
that walls stay upright and ceilings and roofs stay in place. The weight of all the materials in the building
must be balanced by equal and opposite reaction forces. If the forces are not balanced, parts of the building will move in the direction of the resultant force. For each building below say whether you think the
structure is stable or unstable.
5,000kg
2,500kg
30,000kg
2,500kg
25,000kg
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Students aged 11 - 16 years