Answer :
Sure, let's solve this problem step by step.
Part 1: Diagram to show how a shadow is formed
To demonstrate how a shadow is formed, let's consider the following components:
- A flashlight, which serves as the light source.
- A tennis ball, which acts as the opaque object blocking the light.
- A screen, where the shadow is projected.
Here is a simple diagram:
```
Flashlight --> Tennis Ball --> Screen
Light rays emitted from the flashlight will hit the tennis ball, and the ball will block some of the light rays, causing a shadow to form on the screen behind it.
Diagram:
```
Flashlight
.
/ \ Light rays
/ \
/ \
O \
/ \ \
/ \ \
/_____\ \
Tennis Ball \ Shadow
\
\
<-|---------|
| |
| Screen |
| |
| |
|___________|
```
Part 2: Determine the density of an irregular body
To solve the question, let's follow the steps given and the result of the experiment.
### Step-by-Step Solution:
1. Initial Observations:
- The initial volume of water in the graduated cylinder is [tex]\( V_{\text{original}} = 75 \, \text{cm}^3 \)[/tex].
- The volume after immersing the irregular body is [tex]\( V_{\text{after}} = 85 \, \text{cm}^3 \)[/tex].
- The mass of the irregular body is [tex]\( m = 4 \, \text{kg} \)[/tex].
2. Calculate the volume of the irregular body:
- The volume of the irregular body is found by subtracting the original volume from the volume after immersion:
[tex]\[ V_{\text{body}} = V_{\text{after}} - V_{\text{original}} \][/tex]
[tex]\[ V_{\text{body}} = 85 \, \text{cm}^3 - 75 \, \text{cm}^3 = 10 \, \text{cm}^3 \][/tex]
3. Convert the mass to grams:
- Since the volume is in cubic centimeters, we need the mass in grams.
[tex]\[ m_{\text{grams}} = 4 \, \text{kg} \times 1000 = 4000 \, \text{grams} \][/tex]
4. Calculate the density:
- Density ([tex]\( \rho \)[/tex]) is defined as mass divided by volume:
[tex]\[ \rho_{\text{body}} = \frac{m_{\text{grams}}}{V_{\text{body}}} \][/tex]
[tex]\[ \rho_{\text{body}} = \frac{4000 \, \text{grams}}{10 \, \text{cm}^3} = 400 \, \text{g/cm}^3 \][/tex]
So, the density of the body is [tex]\( 400 \, \text{g/cm}^3 \)[/tex].
### Precautions for Reliable Results:
1. Ensure accurate measurement of volumes:
- Ensure that the graduated cylinder is placed on a flat, level surface to avoid any tilting or error in reading the water level.
- Carefully observe and note the water levels before and after immersion, making sure to take readings at eye level to avoid parallax error.
2. Account for complete immersion of the body:
- Make sure that the irregular body is completely submerged in the water to obtain the correct displacement volume.
- Avoid any air bubbles sticking to the surface of the irregular body as they can affect the volume reading.
Taking these precautions will help ensure that the results of the experiment are accurate and reliable.
Part 1: Diagram to show how a shadow is formed
To demonstrate how a shadow is formed, let's consider the following components:
- A flashlight, which serves as the light source.
- A tennis ball, which acts as the opaque object blocking the light.
- A screen, where the shadow is projected.
Here is a simple diagram:
```
Flashlight --> Tennis Ball --> Screen
Light rays emitted from the flashlight will hit the tennis ball, and the ball will block some of the light rays, causing a shadow to form on the screen behind it.
Diagram:
```
Flashlight
.
/ \ Light rays
/ \
/ \
O \
/ \ \
/ \ \
/_____\ \
Tennis Ball \ Shadow
\
\
<-|---------|
| |
| Screen |
| |
| |
|___________|
```
Part 2: Determine the density of an irregular body
To solve the question, let's follow the steps given and the result of the experiment.
### Step-by-Step Solution:
1. Initial Observations:
- The initial volume of water in the graduated cylinder is [tex]\( V_{\text{original}} = 75 \, \text{cm}^3 \)[/tex].
- The volume after immersing the irregular body is [tex]\( V_{\text{after}} = 85 \, \text{cm}^3 \)[/tex].
- The mass of the irregular body is [tex]\( m = 4 \, \text{kg} \)[/tex].
2. Calculate the volume of the irregular body:
- The volume of the irregular body is found by subtracting the original volume from the volume after immersion:
[tex]\[ V_{\text{body}} = V_{\text{after}} - V_{\text{original}} \][/tex]
[tex]\[ V_{\text{body}} = 85 \, \text{cm}^3 - 75 \, \text{cm}^3 = 10 \, \text{cm}^3 \][/tex]
3. Convert the mass to grams:
- Since the volume is in cubic centimeters, we need the mass in grams.
[tex]\[ m_{\text{grams}} = 4 \, \text{kg} \times 1000 = 4000 \, \text{grams} \][/tex]
4. Calculate the density:
- Density ([tex]\( \rho \)[/tex]) is defined as mass divided by volume:
[tex]\[ \rho_{\text{body}} = \frac{m_{\text{grams}}}{V_{\text{body}}} \][/tex]
[tex]\[ \rho_{\text{body}} = \frac{4000 \, \text{grams}}{10 \, \text{cm}^3} = 400 \, \text{g/cm}^3 \][/tex]
So, the density of the body is [tex]\( 400 \, \text{g/cm}^3 \)[/tex].
### Precautions for Reliable Results:
1. Ensure accurate measurement of volumes:
- Ensure that the graduated cylinder is placed on a flat, level surface to avoid any tilting or error in reading the water level.
- Carefully observe and note the water levels before and after immersion, making sure to take readings at eye level to avoid parallax error.
2. Account for complete immersion of the body:
- Make sure that the irregular body is completely submerged in the water to obtain the correct displacement volume.
- Avoid any air bubbles sticking to the surface of the irregular body as they can affect the volume reading.
Taking these precautions will help ensure that the results of the experiment are accurate and reliable.
