A car is traveling at 25 m/s. The driver applies the brakes, and the car decelerates uniformly at 5 m/s². How long does it take for the car to stop, and what distance does it cover during this time?
PhysicsClass 9CBSEAnswered 13 May 2026
Answer
Initial velocity (u) = 25 m/s
Final velocity (v) = 0 m/s (comes to stop)
Acceleration (a) = -5 m/s² (deceleration)
Part 1: Time to stop (t)
Using v = u + at:
0 = 25 + (-5) * t
0 = 25 - 5t
5t = 25
t = 5 seconds.
Part 2: Distance covered (s)
Using v² = u² + 2as:
0² = 25² + 2 * (-5) * s
0 = 625 - 10s
10s = 625
s = 62.5 meters.
Alternatively, using s = ut + (1/2)at²:
s = (25 * 5) + (1/2) * (-5) * (5)²
s = 125 + (1/2) * (-5) * 25
s = 125 - 62.5
s = 62.5 meters.
Suggested Q&A
Physics · Class 9- PhysicsClass 9A ball is dropped from a height. Describe its motion in terms of velocity and acceleration, neglecting air resistance.
- PhysicsClass 9Distinguish between instantaneous speed and average speed. When are they equal?
- PhysicsClass 9A car travels from city A to city B at a speed of 40 km/h and returns from city B to city A at a speed of 60 km/h. What is the average velocity of the car for the entire journey?
- PhysicsClass 9Look at the given velocity-time graph. Describe the motion of the object in each segment (OA, AB, BC).
- PhysicsClass 9Does an object in uniform circular motion have acceleration? If yes, in which direction does it act?
- PhysicsClass 9In uniform circular motion, is the speed constant? Is the velocity constant? Explain your answer.