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Fields and their Consequences Active Recall Answers
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Fields and their Consequences Active Recall ANSWERS:Gravitational fields:
1. What is a force field? Region of space where a body experiences a non
contact force
2. What is a non-contact force? Where a body experience a force without physical
What does it cause to the contact
body it is acting on?
3. What are the three main non Magnetic field, electric fields, gravitational fields
contact forces?
4. How can the direction of a Vector force field line diagrams
force be represented?
5. What are six similarities Both abide by inverse square law
between gravitational and The field lines between a point mass and a negative
electrostatic forces? point charge are identical
The field lines in a uniform gravitational and uniform
electric field are identical
They both have a 1/r2 relationship with field strength
The gravitational and electric potential both have a 1/r
relationship
Equipotential surfaces for both gravitational and
electric fields are spherical around point charge or
mass and equally spaced parallel lines in uniform fields
The work done is either the product of the mass and
change in potential or charge and change in potential.
6. What are three differences Gravitational force is always attractive, whereas the
between gravitational and electrostatic can be both attractive or repulsive
electrostatic forces? The gravitational acts on mass, whilst the electric acts
on charged particles
The gravitational potential is always negative, whilst
electric potential can be positive or negative
7. What is responsible for the The earth’s gravitational field
weight of all objects on
earth?
8. What is a gravitational field A region of space where a mass experience a force due
defined as? to a gravitational attraction to another mass.
9. What is the direction of a Towards the centre of mass
gravitational field?
10.Are gravitational forces Attractive
attractive or repulsive?
11.What is the range of gravity? Infinite range
12.How is the strength of a G=F/m
gravitational field calculated
at a point?
13.What factors affect the The radius (or diameter) of the planet, the mass (or
gravitational field strength at density) of the planet
the surface of a planet?
14.How is the direction of a Gravitational field lines
gravitational field
represented?
15.On a point mass, how are Radially inwards
the gravitational field lines
drawn?
16.On a uniform field, how are Equally space parallel lines
, the gravitational field lines
drawn?
17.What does it mean for The gravitational field strength is different depending
something to have a non- on the distance from the centre
uniform field?
18.What is a uniform field? Parallel lines, where the gravitational field strength is
the same throughout.
19.What makes a sphere Where the mass is distributed evenly
uniform?
20.When can an object be When the body covers a very large distance compared
regarded as a point mass? to its size, so to study its motion, its size or dimensions
can be neglected.
21.When does Newton’s law of For two bodies outside a uniform field
gravitation apply?
22.What is Newton’s law of The gravitational force between two point masses is
gravitation? proportional to the product of their masses and
inversely proportional to the square of their separation.
23.What law does Newton’s law Inverse square law
of gravitation follow?
24.How can the gravitational
field strength of a radial field
be calculated?
25.As you get further from the Are r increases, g decreases
earth’s surface, how does
the value of g change?
26.What does the graph look When r is smaller than the radius of the planet, g is
like for g plotted against the directly proportional to r. When r is greater than the
distance from the centre of a radius of the planet, g is inversely proportional to r 2. So
planet? the graph looks like a positive linear until R, then from
above that, it’s a negative curve.
27.What is gravitational Energy an object has when lifted off the ground
potential energy?
28.How do you calculate the Mgh, only when the objects rae within the earth
gravitational potential surface.
energy?
29.What is the GPE on the Zero, as you need to do work to take something off the
surface of the earth surface of the earth.
30.What is the gravitational The work done per unit mass in bringing a test mass
potential at a point defined from infinity to a defined point.
as?
31.Is gravitational potential Negative
positive or negative?
32.Why is gravitational potential The potential is defined as zero at infinity and since the
a negative value? gravitational force is attractive, work must be done on
the mass to reach infinity. The gravitational potential is
negative on the suface of a mass, and increases with
distance from the mass and becomes less negative to
reach zero. Work has to be done against gravitational
pull of the planet to take a unit mass away from the
planet.
33.At infinity, what is the value 0
of gravitational potential?
34.What needs to be done to a Work needs to be done against the gravitational pull of
, mass to make it reach the planet to take a mass away from the planet.
infinity? Why?
35.What is gravitational The difference in potential between two points that are
potential difference? different distances away from the mass.
36.What equation is used to find
the gravitational potential?
37.Is potential a scalar or vector Scalar
quantity?
38.As a mass moves away from Larger, less negative, unitl it reaches zero at infinity
a planet, does the
gravitational potential
become smaller or larger?
Why?
39.What can a graph of The values of V are all negative
gravitational potential As r increases, V against r follows a -1/r relationship
against the distance from The gradient of the graph at any point is the value of g
point mass show? at that point.
The graph has a shallow increase as r increases.
40.What relationship do r and V As r increases, V against r follows a -1/r relationship
have on a V-r graph?
41.What should a V-r graph look 4th quadrant. Low value of V, high value of r, r
like? increases as v gets closer to zero
42.What can a graph of The values og g are always positive
gravitational field strength As r increases, g against r follows a 1/r2 relationship
against the distance from The area under the graph is gravitational potential
point mass show? The graph has a steep decline as r increases
43.What relationship do r and g As r increases, g against r follows a 1/r2 relationship
have on a g-r graph?
44.What should a g-r graph look Negative curve, asymptote at the r value of surface of
like? the planet, as no value of g for r value less than the
radius of the planet.
45.How would you calculate the W=mV= mass x gravitational potential
work done in moving a
mass?
46.When a mass is moved
against the force of gravity,
what is the work done equal
to at that point?
47.Which situation can the mgh When an object is lifted in a unfirom gravitational field,
equation be used in? close to the earths surface.
48.What is an equipotential Points that join together that have the same
line? gravitational potential
49.What do the equipotential Concentric circles around the planet.
lines look like for a radial Become further apart as you get further away from the
field? planet.
50.What do the equipotential Straight parallel lines, horizontal, equally spaced
lines look like for a uniform
field?
51.What work is done when 0 work done when moving alone, only between
moving along an surfaces is there work done.
equipotential surface, and
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