Transcript How do you work out speed?

Additional Physics – Forces
Exam Date -
“Hooke’s
law”
L/O :- To know Hooke’s law
Quick quiz
• What can the motion be like of an object with
BALANCED forces? (2 marks)
• What can the motion be like of an object with
UNBALANCED forces (2 marks)
• How do you work out speed?
• What 2 equations can you use to work out acceleration?
• What is acceleration measured in?
• What 2 things affect stopping distance?
• Name 3 things that affect thinking distance
• Name 3 things that affect braking distance
• What is terminal velocity and what are the forces like on
an object that has reached terminal velocity?
‘A force acting on an object can cause the object to
change shape’. Does this clip show this?
These results show the distance
travelled by an object using a catapult
Extension of catapult (cm)
How far object travels (m)
10
2
20
6
30
8
40
12
Draw a sketch graph
of these results.
What do they tell
you about the
relationship between
extension and
distance travelled?
What type of energy
is stored in a piece of
elastic or spring?
Distance
travelled
(m)
Extension of catapult (cm)
Just like elastic, a spring can
also apply a force.
Hooke’s Law – The
extension of a spring is
directly proportional to
the force applied to it
What do you
remember about
the force applied
to a spring and
the extension?
This is how a Newton
meter works
The amount of force
required to stretch the
spring a given amount is
called the spring
constant
The equation for Hooke’s law is
Force applied = spring constant x extension
(N)
(N/m)
(m)
TASK
You are going to be given a number of springs. We
know what the spring constant is for each. Your task
is to work out, as accurately as possible, the spring
constant for each spring. There will be a prize for
the group which gets the most accurate result for
each spring
What did you do to
increase the accuracy
of your results?
What could have
caused errors in your
results?
So what do we know?
How does the stiffness of a
spring affect the spring
constant?
What have you learnt?
• Do you know what Hooke’s law is?
• Do you know what the spring constant is?