NOTE ONLY Answer quetuin 6 and 7

6: Show how the time to fall a distance d = 1 m on earth would change if this experiment was conducted on the moon.

7: Show how the time to fall a distance d = 1 m on earth would change if the mass of the ruler was doubled.

Lab 2: Free Fall - Measuring Reaction Time

Purpose

To measure your reaction time to catch a falling ruler.

Background

The position of an object dropped from rest and falling freely under the influence of gravity is given by:

where d = the distance the object drops

= acceleration due to gravity = 9.8 m/s² = 980 cm/s²

t = time of fall

Materials and Equipment

• 30-cm Ruler
• Table edge

Procedure

• Place your RIGHT hand on the edge of a table with the fingers and thumb sticking out over the edge.
• Open your fingers so they are 10 cm away from your thumb.
• Have a partner hold a ruler near the 30 cm mark and let it hang vertically even with the top of your fingers and thumb. The zero mark on the ruler should be closest to the floor.

NO WARNING OR CLUES

• As fast as possible, catch the ruler when your partner lets it drop.
• In the data table below, record the number on the ruler showing above your finger and thumb.
• Repeat four times.
• Repeat the testing and recording using your LEFT hand.

WARNING OR CLUES GIVEN

• Get your RIGHT hand ready to catch the ruler.
• Have a partner hold a ruler even with the top of your fingers and thumb.
• Your partner counts to three then lets the ruler drop on THREE.
• As fast as possible, catch the ruler when your partner lets it drop.
• Repeat four times and record the number showing above your finger and thumb.
• Repeat the testing and recording using your LEFT hand.

Data

Complete the data table using consistent units. For each type of drop, calculate the average drop distance and your reaction time.

Centimeter Reading above Your Thumb

Type of Drop	Trial 1 d1 (cm)	Trial 2 d2 (cm)	Trial 3 d3 (cm)	Trial 4 d4 (cm)	Average Drop Distance, d (cm)	Your Reaction Time, t (s)
Right Hand No Warning
Left Hand No Warning
Right Hand with Warning
Left Hand with Warning

Data Analysis

1. Copy and paste the completed data table in your lab report 2.
2. At what type of drop was your best reaction time?
3. At what type of drop was your worst reaction time?
4. Is your worst reaction time faster or slower than 0.2 s, the average human reaction time?
5. List three factors that would affect the human reaction time in general.
6. Show how the time to fall a distance d = 1 m on earth would change if this experiment was conducted on the moon.
7. Show how the time to fall a distance d = 1 m on earth would change if the mass of the ruler was doubled.
8. Solve this exercise about keeping a safe distance while driving. You are driving down the highway late one night at 20 m/s when a deer steps onto the road 35 m in front of you. Your reaction time before stepping on the brakes is 0.50 s, and the maximum deceleration of your car is 10 m/s². How much distance is between you and the deer when you come to a stop

Reporting

After completing your data analysis, type your findings in the provided Lab Report 2 and submit for grading.