Grade 9 Science TestSummative - Compute For The Following: (5 Points Each)1. Andrei Is Driving Down 7th Street. He Drives 150 Meters In 18 Seconds. Assuming He Does Not Speed Up Or Slow Down, What Is His Speed In Meters Per Second?2. Sound Travels At A
Grade 9 Science Test: Summative
Physics Section
Question 1: Computing Speed
Andrei is driving down 7th street. He drives 150 meters in 18 seconds. Assuming he does not speed up or slow down, what is his speed in meters per second?
Understanding the Problem
To solve this problem, we need to understand the concept of speed and how it is calculated. Speed is defined as the distance traveled per unit time. In this case, we are given the distance traveled (150 meters) and the time taken (18 seconds). We need to use these values to calculate Andrei's speed in meters per second.
Calculating Speed
The formula to calculate speed is:
Speed = Distance / Time
In this case, the distance is 150 meters and the time is 18 seconds. Plugging these values into the formula, we get:
Speed = 150 meters / 18 seconds
To simplify this expression, we can divide 150 by 18:
Speed = 8.33 meters/second
Therefore, Andrei's speed is 8.33 meters per second.
Understanding the Significance of Speed
Speed is an important concept in physics, as it is related to many other physical quantities such as velocity, acceleration, and force. In this case, knowing Andrei's speed can help us understand how fast he is moving and how long it will take him to cover a certain distance.
Question 2: Computing Speed of Sound
Sound travels at a speed of 343 meters per second in air at room temperature. What is the time taken for sound to travel 245 meters?
Understanding the Problem
To solve this problem, we need to use the formula for speed, which is:
Speed = Distance / Time
We are given the speed of sound (343 meters per second) and the distance it travels (245 meters). We need to use these values to calculate the time taken for sound to travel 245 meters.
Calculating Time
Rearranging the formula for speed to solve for time, we get:
Time = Distance / Speed
Plugging in the values, we get:
Time = 245 meters / 343 meters/second
To simplify this expression, we can divide 245 by 343:
Time = 0.71 seconds
Therefore, it takes approximately 0.71 seconds for sound to travel 245 meters.
Understanding the Significance of Speed of Sound
The speed of sound is an important concept in physics, as it is related to many other physical quantities such as frequency, wavelength, and pressure. In this case, knowing the speed of sound can help us understand how fast sound travels and how long it will take for sound to reach us from a distant source.
Question 3: Computing Distance
A car is traveling at a speed of 25 meters per second. What is the distance traveled by the car in 15 seconds?
Understanding the Problem
To solve this problem, we need to use the formula for speed, which is:
Speed = Distance / Time
We are given the speed of the car (25 meters per second) and the time it travels (15 seconds). We need to use these values to calculate the distance traveled by the car.
Calculating Distance
Rearranging the formula for speed to solve for distance, we get:
Distance = Speed x Time
Plugging in the values, we get:
Distance = 25 meters/second x 15 seconds
To simplify this expression, we can multiply 25 by 15:
Distance = 375 meters
Therefore, the car travels a distance of 375 meters in 15 seconds.
Understanding the Significance of Distance
Distance is an important concept in physics, as it is related to many other physical quantities such as speed, velocity, and acceleration. In this case, knowing the distance traveled by the car can help us understand how far it has traveled and how long it will take to cover a certain distance.
Question 4: Computing Time
A person is walking at a speed of 2 meters per second. What is the time taken for the person to walk 120 meters?
Understanding the Problem
To solve this problem, we need to use the formula for speed, which is:
Speed = Distance / Time
We are given the speed of the person (2 meters per second) and the distance they walk (120 meters). We need to use these values to calculate the time taken for the person to walk 120 meters.
Calculating Time
Rearranging the formula for speed to solve for time, we get:
Time = Distance / Speed
Plugging in the values, we get:
Time = 120 meters / 2 meters/second
To simplify this expression, we can divide 120 by 2:
Time = 60 seconds
Therefore, it takes 60 seconds for the person to walk 120 meters.
Understanding the Significance of Time
Time is an important concept in physics, as it is related to many other physical quantities such as speed, velocity, and acceleration. In this case, knowing the time taken for the person to walk 120 meters can help us understand how long it will take to cover a certain distance.
Question 5: Computing Speed
A train is traveling at a speed of 50 meters per second. What is the speed of the train in kilometers per hour?
Understanding the Problem
To solve this problem, we need to convert the speed of the train from meters per second to kilometers per hour. We can do this by using the conversion factor:
1 meter/second = 3.6 kilometers/hour
Calculating Speed
We can convert the speed of the train by multiplying it by the conversion factor:
Speed (km/h) = 50 meters/second x 3.6 kilometers/hour/meter/second
To simplify this expression, we can multiply 50 by 3.6:
Speed (km/h) = 180 kilometers/hour
Therefore, the speed of the train is 180 kilometers per hour.
Understanding the Significance of Speed
Speed is an important concept in physics, as it is related to many other physical quantities such as velocity, acceleration, and force. In this case, knowing the speed of the train can help us understand how fast it is moving and how long it will take to cover a certain distance.
Conclusion
In this section, we have solved five problems related to speed, distance, and time. We have used the formulas for speed, distance, and time to calculate the values of these quantities in different scenarios. We have also discussed the significance of these quantities in physics and how they are related to each other.
Grade 9 Science Test: Summative
Physics Section
Q&A: Speed, Distance, and Time
Q1: What is the difference between speed and velocity?
A1: Speed is a scalar quantity that refers to the rate at which an object moves, while velocity is a vector quantity that includes both the speed and direction of an object.
Q2: How do you calculate the speed of an object?
A2: To calculate the speed of an object, you need to divide the distance traveled by the object by the time taken to travel that distance. The formula for speed is:
Speed = Distance / Time
Q3: What is the unit of speed?
A3: The unit of speed is meters per second (m/s) or kilometers per hour (km/h).
Q4: How do you convert meters per second to kilometers per hour?
A4: To convert meters per second to kilometers per hour, you can multiply the speed in meters per second by 3.6.
Q5: What is the difference between distance and displacement?
A5: Distance is a scalar quantity that refers to the total length of the path traveled by an object, while displacement is a vector quantity that refers to the shortest distance between the initial and final positions of an object.
Q6: How do you calculate the distance traveled by an object?
A6: To calculate the distance traveled by an object, you need to multiply the speed of the object by the time taken to travel that distance. The formula for distance is:
Distance = Speed x Time
Q7: What is the unit of distance?
A7: The unit of distance is meters (m) or kilometers (km).
Q8: How do you calculate the time taken to travel a certain distance?
A8: To calculate the time taken to travel a certain distance, you need to divide the distance by the speed of the object. The formula for time is:
Time = Distance / Speed
Q9: What is the difference between speed and acceleration?
A9: Speed is a scalar quantity that refers to the rate at which an object moves, while acceleration is a vector quantity that refers to the rate at which an object's speed changes.
Q10: How do you calculate the acceleration of an object?
A10: To calculate the acceleration of an object, you need to divide the change in speed by the time taken to achieve that change in speed. The formula for acceleration is:
Acceleration = Change in Speed / Time
Conclusion
In this Q&A section, we have discussed various concepts related to speed, distance, and time. We have also provided formulas and examples to help you understand these concepts better. We hope this section has been helpful in clarifying any doubts you may have had about these topics.
Additional Resources
If you need further clarification on any of the concepts discussed in this section, you can refer to the following resources:
- Textbooks on physics and mathematics
- Online resources such as Khan Academy and Crash Course
- Practice problems and quizzes to test your understanding of the concepts
Practice Problems
Try solving the following practice problems to test your understanding of the concepts discussed in this section:
- A car travels at a speed of 60 km/h for 2 hours. What is the distance traveled by the car?
- A person walks at a speed of 5 km/h for 3 hours. What is the distance traveled by the person?
- A train travels at a speed of 80 km/h for 1 hour. What is the distance traveled by the train?
- A bicycle travels at a speed of 20 km/h for 2 hours. What is the distance traveled by the bicycle?
- A bus travels at a speed of 40 km/h for 3 hours. What is the distance traveled by the bus?
Answer Key
- 120 km
- 15 km
- 80 km
- 40 km
- 120 km