Motion and Its Description

v = u + at

Step 1: This is the first equation of motion derived from the definition of acceleration. Step 2: Acceleration (a) = (final velocity - initial velocity)/time = (v - u)/t. Step 3: Rearranging: a × t = v - u. Step 4: Therefore: v = u + at, where v = final velocity, u = initial velocity, a = acceleration, t = time. Step 5: This equation helps us find final velocity when we know initial velocity, acceleration, and time taken.

50 km/h

Step 1: Average speed is calculated using the formula: Average speed = Total distance/Total time. Step 2: Given: Total distance = 200 km, Total time = 4 hours. Step 3: Average speed = 200 km ÷ 4 hours = 50 km/h. Step 4: This means the car covers 50 kilometers every hour on average. Step 5: Note that average speed may differ from instantaneous speed at any given moment during the journey.

Rest

Step 1: In a position-time graph, the x-axis represents time and y-axis represents position. Step 2: A horizontal line means position remains constant as time passes. Step 3: If position doesn't change with time, the object is not moving. Step 4: Therefore, a horizontal line indicates the object is at rest. Step 5: The slope of this line is zero, confirming zero velocity (no motion).

The tip of a clock's second hand

Step 1: Uniform circular motion requires constant speed along a circular path. Step 2: The tip of a clock's second hand moves in a perfect circle around the center. Step 3: It covers equal distances (equal arc lengths) in equal time intervals. Step 4: The speed remains constant, but direction continuously changes. Step 5: Other options involve either non-circular paths or non-uniform motion patterns.