# INVESTIGATING HOW STEEPNESS AFFECTS SPEED

INVESTIGATING HOW STEEPNESS AFFECTS SPEED

PLAN

## Aim

The aim of this investigation is to find how the steepness of a ramp affects the speed of a ball rolling down it.

Prediction

I predict that the steeper the ramp the faster a ball will roll down it. So their will be greater acceleration i.e. the ball will speed up. This is because their will be less resultant force as the ramp gets steeper. I can back my prediction by using forces as part of my hypothesis.

Research

## Newton’s laws of motion

• 1st law- balanced forces mean no change in velocity

So long as the forces of an object are all balanced it’ll just stay still or else if   it’s already moving it’ll just carry on at the same velocity.

• 2nd law- a resultant force means acceleration

If there is an unbalanced force, then the object will accelerate in that direction.

The reaction force

Is always 90°C from the slope

As the ramp gets steeper there is less reaction force balancing the weight so there is greater resultant force.

• 3rd law- reaction forces

If object A exerts a force on object B then object B exerts the exact opposite force on object A.

Whenever an object is on a horizontal surface, there’ll always be a reaction force pushing upwards, supporting the object.  The total reaction force will be equal and opposite of the weight.

In the above diagram the object is not on a horizontal surface there is no reaction force pushing upwards, therefore the resultant forces is greatest when the slope is vertical.

Variables

The two changing variables in this experiment are:

• The speed of the ball
• The height of the ramp.

There are many controlled variables to consider in this experiment such as the size and mass of ball, surface type (ball and ramp) force of the push and the distance rolled/ length of slope.

Expected results

Speed

(cm per

second)

Steepness (cm)

All the research I have collected from Edexel Modular science –revision guide: book two

#### Preliminary run

I did a preliminary run to help me improve my knowledge about the experiment

• I collected the following equipment: ruler, ball, ramp, books, and stop clock

(I collected the bigger ramp because I know that with a bigger one I would have fewer errors).

• I then weighed the mass of the 3 balls, which I chose to use.
• Next I placed the ramp on the books, and measured its vertical height.
• I marked my starting and finishing points and them measured the distance of how much the balls were going to roll.
• I rolled the 3 different balls 3 times each and recorded the time it took them.

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