Physics
Lab 1.12 Marble and Chute
We can tell the velocity
of a horizontally launched object from the height that it
is launched from and the distance it travels in the time
taken to drop to the ground. In this experiment we use a
chute to accelerate an marble horizontally and estimate
it’s horizontal velocity from the distance it
travels horizontally before hitting the floor. For
comparison, we assume that no energy is lost while it
rolls down the chute and estimate its velocity from the
conversion of gravitational potential energy to kinetic
energy in the chute.
Set up the chute as
illustrated in the video lesson and carry out the
experiments described below.
Record the results of the
experiment in the table provided and perform the
calculations needed to complete the table.
- Relative to its
height when it reaches the end of a chute, a
steel ball with a mass of 50 g situated 30cm
above the end of the chute has gravitational
potential energy = 0.147J . If no energy is lost
due to friction as it rolls down the chute, how
much kinetic energy does it have when it reaches
the end of the chute?
- Calculate the speed
of the steel ball from its kinetic energy.
- If the ball leaves
the chute horizontally from the edge of a table
75 cm above the floor, how much time will it take
for the ball to reach the floor?
- If, during this time,
the ball covers a horizontal distance of 70 cm,
what was its horizontal velocity when it left the
edge of the table?
Experiment 1.12.A
Marble and Chute
The purpose of this
experiment is to estimate the horizontal speed of a
marble that is launched horizontally from the edge of a
table.
Materials and Equipment
- Marble
- A chute – This
can be built or purchased
- Large sheet of paper
- Carbon paper
- Tape measure
- Piece of string (1.5m)
and a small weight (or a spirit level)
- Small container to
aim the marble at
Procedure
- Mount the chute so
that the marble leaves the chute near to the edge
of a table.
- Place markings on the
chute mounting that indicate various heights
above the table surface.
- Allow the marble to
roll from a particular point and note where it
lands on the floor.
- Repeat this – it
should land at the same place each time.
- Measure the vertical
distance from the edge of the table to the floor.
- Use the string and
weight or the spirit level to locate a point on
the paper on the floor directly below the point
on the edge of the table where the marble left
the chute.
- Measure the distance
from this point to the point at which the marble
landed.
- The point at which
the marble lands can be identified by placing a
large piece of white paper on the floor and
placing a piece of carbon paper facing downwards
on the paper in the region where the marble is
expected to land. The impact of the marble on the
carbon paper makes a mark on the white paper
below.
- Allow the marble to
roll down the chute from three or four different
heights above the table and record the distance
traveled before it hits the floor.
- Enter the results in
the table below and complete the table by
performing the necessary calculations.
Calculations
The speed of the marble
when it leaves the chute can be calculated from the
height that it was allowed to roll from.
Compare this with the
distance that it traveled in the air before it hit the
ground.
Assuming it was traveling
horizontally when it left the chute, it started
accelerating towards the floor at a rate of 9.81 m/s2
as soon as it left the edge of the table. The time taken
to reach the floor can be calculated from the equation: d
= ˝gt2 where d is the distance in meters (The
height of the table), g is 9.81 m/s2 and time,
t, is measured in seconds.
The speed of the marble
can be calculated from the distance from the point on the
floor below where it left the edge of the table to the
point at which it landed on the floor divided by the time
taken.
Results
Mass of marble = M grams (not
needed)
Height of table top above
floor = ……………….cm.
Time for marble to drop
this distance = …….……seconds.
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Marble’s height
above table at start of roll
(cm
above table top)
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Gravitational potential
energy of marble that was converted to kinetic
energy
(Joules)
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Velocity of marble
calculated from kinetic energy
(m/s)
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Horizontal distance from
edge of table to point at which it landed on the
floor
(cm)
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Horizontal velocity of
marble calculated from time to drop
(m/s)
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30
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2.94M (M is mass)
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1.41
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69
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1.8
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Typical results
Physics
Lab 1.12B Trebuchet Performance
Test the performance of a model trebuchet (constrcted as
part of Project # 3) by measuring the distances traveled
by different sized projectiles.
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