Physics Summary
1.1 GRAVITY AND GRAVITATIONAL FIELDS
1.1.1 Define weight as the force on an object due to a gravitational field.
Weight is the force experienced by an object due to the presence of a gravitational field. This force is directly related to the strength of the gravitational field acting on an object and the mass of that object.
m = mass, g = acceleration due to gravity m = mass, g = acceleration due to gravity
Fg = mg
Fg = mg
1.1.2 Explain that a change in gravitational energy is related to work done.
Work done is the measure of how much energy is required to displace an object a specified distance.
F = Force, s = displacement
F = Force, s = displacement
W = Fs
W = Fs
When an object is moved away from a gravitational field, it gains energy. This is because by raising it up from the field’s origin, work is done.
E.g. An object 1kg in mass is raised 100m, the work done would be 980J. However, conservation of energy states that energy cannot be destroyed. Therefore the object now has 980J in gravitational potential energy. Whereas at the origin is would have 0J potential energy. Fg = Gm1m2d2 Fg = Gm1m2d2
Ep =
1.1.3 Perform an investigation and gather information to determine a value for acceleration due to gravity using the pendulum motion or computer assisted technology and identify reasons for possible variations in the value 9.8m.s-1
AIM: To measure the value of acceleration due to gravity on the surface of the earth.
APARATUS: A weight attached to a thick, non-elastic string that was tied to a clamp on a retort stand.
METHOD:
1) Set the pendulum in motion, making sure it doesn’t swing in a deflection greater than 30° (as greater than 30° will cause the string to lose tension) 2) Using a stopwatch, time the pendulum’s swing over 10 complete cycles (periods). Starting at the middle of the swing, and timing until it returned to the centre of its swing. 3) Using the formula:
1.1.1 Define weight as the force on an object due to a gravitational field.
Weight is the force experienced by an object due to the presence of a gravitational field. This force is directly related to the strength of the gravitational field acting on an object and the mass of that object.
m = mass, g = acceleration due to gravity m = mass, g = acceleration due to gravity
Fg = mg
Fg = mg
1.1.2 Explain that a change in gravitational energy is related to work done.
Work done is the measure of how much energy is required to displace an object a specified distance.
F = Force, s = displacement
F = Force, s = displacement
W = Fs
W = Fs
When an object is moved away from a gravitational field, it gains energy. This is because by raising it up from the field’s origin, work is done.
E.g. An object 1kg in mass is raised 100m, the work done would be 980J. However, conservation of energy states that energy cannot be destroyed. Therefore the object now has 980J in gravitational potential energy. Whereas at the origin is would have 0J potential energy. Fg = Gm1m2d2 Fg = Gm1m2d2
Ep =
1.1.3 Perform an investigation and gather information to determine a value for acceleration due to gravity using the pendulum motion or computer assisted technology and identify reasons for possible variations in the value 9.8m.s-1
AIM: To measure the value of acceleration due to gravity on the surface of the earth.
APARATUS: A weight attached to a thick, non-elastic string that was tied to a clamp on a retort stand.
METHOD:
1) Set the pendulum in motion, making sure it doesn’t swing in a deflection greater than 30° (as greater than 30° will cause the string to lose tension) 2) Using a stopwatch, time the pendulum’s swing over 10 complete cycles (periods). Starting at the middle of the swing, and timing until it returned to the centre of its swing. 3) Using the formula: