A car covers 60 km in the first hour, 70 km in the second hour, and 50 km in the third hour. Is the motion uniform? Justify your answer. Find the average speed of the car.
The motion is non-uniform because the car covers unequal distances (60 km, 70 km, and 50 km) in equal time intervals of one hour each.
For uniform motion, the object must cover equal distances in equal intervals of time.
The average speed of the car is 60 km/h.
Explanation
The chapter defines uniform linear motion as motion where an object covers equal distances in equal intervals of time. In this case, the distances covered in three equal time intervals (each one hour) are different: 60 km, 70 km, and 50 km. Therefore, the motion is non-uniform. Average speed is calculated as total distance divided by total time, as stated in the chapter.
Solution Steps
Step 1: Check for uniform motion: Compare distances covered in equal time intervals
Step 2: First hour: 60 km, Second hour: 70 km, Third hour: 50 km
Step 3: Since 60 70 50, distances are unequal in equal time intervals
Step 4: Conclusion: Motion is non-uniform
Step 5: Calculate total distance: 60 + 70 + 50 = 180 km
Step 6: Calculate total time: 1 + 1 + 1 = 3 hours
Step 7: Calculate average speed: 180 km / 3 h = 60 km/h