PT3 KSSM Mathematics Form 2 (Speed And Acceleration) Chapter 9 Complete Revision

Summary

In this educational video, Teacher Daisy teaches Form 2 Mathematics, focusing on Chapter 9: Speed and Acceleration. She explains the concepts of speed as a rate of distance over time, using examples like Aida's walk and sprinters' races to illustrate calculations. Daisy differentiates between uniform and non-uniform speed, provides examples, and explains acceleration as the rate of speed change. She covers average speed, acceleration units, and conversions between km/h and m/s. The video concludes with a practical example of calculating acceleration differences for a trip to a cultural festival.

Takeaways

• 📏 **Speed Calculation**: Speed is calculated as distance over time, e.g., Aida's speed is 20 meters per minute.
• 🏃 **Sprinter's Speed**: Hyrule's speed is 9.82 meters per second, and Badrill's speed is 9.76 meters per second in a 100-meter sprint.
• 🔄 **Uniform vs. Non-uniform Speed**: Uniform speed covers equal distances in equal time intervals, while non-uniform speed covers unequal distances.
• 🚗 **Gradient and Speed**: Fari's driving speed is non-uniform as the distances covered in different time intervals are not equal.
• 🏌️ **Uniform Speed in Golf**: The golf ball has a uniform speed as it covers equal distances in equal time intervals.
• 🚴 **Average Speed**: Average speed is the total distance over the total time, e.g., Amir's average speed is 10.77 kilometers per hour.
• ⏱️ **Acceleration**: Acceleration is the increase in speed over time, e.g., a bike race example shows an acceleration of 3 meters per second per second.
• 🚗 **Car Acceleration**: A racing car's acceleration can be calculated by the change in speed over time, resulting in 0.0056 kilometers per second squared.
• 🏍 **Motorcycle Acceleration**: A motorcycle's acceleration is 4 meters per second squared when it reaches 20 meters per second in 5 seconds.
• 🛑 **Deceleration**: Deceleration is the decrease in speed, shown as negative acceleration, e.g., -5 meters per second squared for a motorcycle stopping.
• 🔄 **Unit Conversion**: Conversion between kilometers per hour and meters per second involves understanding the relationship between these units.

Q & A

What is the formula for calculating speed?

Speed is calculated as distance divided by time. The formula is: Speed = Distance / Time.

In the example of Aida walking 100 meters in 5 minutes, how is her speed calculated?

Aida's speed is calculated by dividing the distance she walked (100 meters) by the time taken (5 minutes). So, Speed = 100 meters / 5 minutes = 20 meters per minute.

What is the difference between uniform and non-uniform speed?

Uniform speed means covering equal distances in equal intervals of time, while non-uniform speed means covering unequal distances in equal intervals of time.

In the example of Fari driving a trailer, why is the speed considered non-uniform?

Fari's speed is non-uniform because he covered different distances in different time intervals. For the first 2 hours, he traveled at 85 km/h, but for the next 4 hours, his speed decreased to 47.5 km/h.

How is average speed calculated?

Average speed is calculated by dividing the total distance traveled by the total time taken. The formula is: Average Speed = Total Distance / Total Time.

What is acceleration, and how is it different from speed?

Acceleration is the rate at which an object’s speed changes over time, while speed is the distance covered per unit of time. Acceleration can be positive (increase in speed) or negative (deceleration or decrease in speed).

How is acceleration calculated in the example of a racing car reaching 120 km/h in 6 seconds?

First, convert 120 km/h to km/s, which equals 0.033 km/s. Then, use the formula for acceleration: Acceleration = Change in Speed / Time = 0.033 km/s / 6 seconds = 0.0056 km/s².

What is the formula for converting speed from kilometers per hour to meters per second?

To convert kilometers per hour to meters per second, multiply the speed by 5/18. The formula is: Speed (m/s) = Speed (km/h) * 5/18.

How is deceleration calculated when a motorcycle slows down from 20 m/s to 0 in 4 seconds?

Deceleration is calculated using the formula: Deceleration = (Final Speed - Initial Speed) / Time. In this case, Deceleration = (0 - 20 m/s) / 4 seconds = -5 m/s². The negative sign indicates deceleration.

What is the difference in acceleration between Ronnie’s trips to and from the cultural festival?

Ronnie’s acceleration when going to the festival is 24 km/h², while during the return trip, it is 40 km/h². The difference in acceleration is 16 km/h².