Projectile Motion

Projectile Motion


To investigate the trajectory of a small ball as it rolls off a surface which is inclined to the horizontal.


To investigate the trajectory of a two dimensional motion


* Ramp

* Wooden block

* Pendulum bob

* Plumb line

* Steel ball

* Wooden board

* Carbon paper

* Meter rule
* Plasticine


1. A ramp has been set up at the edge of a bench as shown in the Figure 4-1.

2. Suspend a plum-line from the edge of the bench as shown in Figure 4-2.

3. Mount a wooden board horizontally using two clamps so that the board is situated

about the bottom of the ramp.

4. Place a sheet of blank paper on top of the board.

5. Place a piece of carbon paper on the top of the blank paper. The ink-side of the

carbon paper should be facing down.

6. When a ball is released at the top of the ramp, the ball will travel through a

trajectory as shown in Figure 4-2.


g = 9.8 ms-2

u = speed of the ball as it leaves the ramp

k = constant

y = vertical distance (between the bottom of the ramp and the top of the board)

x = horizontal distance (between the plum-line and mark on the paper)

The equation which relates to x and y is



1. Position the ball at the top of the ramp. Release the ball so that it rolls down the

ramp and onto the board below.

2. Remove the carbon paper and observe that the ball makes a small mark on the blank


3. Measure and record the vertical distance y and the horizontal distance x.

4. Reduce the value of y and repeat the steps above to obtain five sets of values of

x and y.

5. Tabulate: y, x, and yx

6. Plot a graph of yx against x.

7. Determine the gradient and y- intercept of the graph.

8. Use your answer from [7] to determine values of k and u.



(±0.1) | y/cm

(±0.1) | yx |

16.6 | 50.0 | 3.012 |

14.5 | 45.0 | 3.103 |

13.2 | 40.0 | 3.030 |...

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