Motion Under Gravity
A stone is dropped from the top of a tower and reaches the ground in 4 seconds, taking g equal to 10 m/s², what is the height of the tower?
Select the correct option:
🔒 Solution Hidden from View
Submit your answer to unlock the detailed step-by-step solution.
More kinematics Practice Questions
A stone is dropped from rest at the top of a tower and reaches the ground after 3 seconds of free fa...
A stone is dropped from rest at the top of a tower and reaches the ground after 3 seconds of free fa...
A ball is thrown vertically upward with a velocity of 20 m/s. What will be its velocity when it retu...
A ball is thrown vertically upward with a velocity of 20 m/s. What will be its velocity when it retu...
A javelin is launched at 40 m/s at 45 degrees to the horizontal across a level field, with g equal t...
A javelin is launched at 40 m/s at 45 degrees to the horizontal across a level field, with g equal t...
Among the following physical quantities encountered in motion, which one is correctly classified as ...
Among the following physical quantities encountered in motion, which one is correctly classified as ...
A particle is said to be in uniform motion along a straight line when which of the following conditi...
A particle is said to be in uniform motion along a straight line when which of the following conditi...
A particle moves 8 m east and then 6 m north in a total time of 5 seconds along a flat surface, what...
A particle moves 8 m east and then 6 m north in a total time of 5 seconds along a flat surface, what...
A body starting from rest moves with uniform acceleration of 6 m/s² along a straight road, what dist...
A body starting from rest moves with uniform acceleration of 6 m/s² along a straight road, what dist...
A swimmer who can swim at 4 m/s in still water heads straight across a river flowing at 3 m/s, what ...
A swimmer who can swim at 4 m/s in still water heads straight across a river flowing at 3 m/s, what ...
A ball thrown vertically upward with an initial speed of 20 m/s reaches its highest point, taking g ...
A ball thrown vertically upward with an initial speed of 20 m/s reaches its highest point, taking g ...
From the top of a building a ball is dropped just as another ball is thrown up from the ground at 25...
From the top of a building a ball is dropped just as another ball is thrown up from the ground at 25...
The position of a particle along a straight line varies with time as x equals 2t cubed minus 3t squa...
The position of a particle along a straight line varies with time as x equals 2t cubed minus 3t squa...
The slope of a position-time graph at any instant for a moving particle physically represents which ...
The slope of a position-time graph at any instant for a moving particle physically represents which ...
About This Question
- Subject
- physics
- Chapter
- kinematics
- Topic
- motion under gravity
- Difficulty
- Easy
- Year
- 2025
Solution
Correct Answer:
80 m
Following NCERT Class 11, Chapter 3 (Motion in a Straight Line), an object in free fall under gravity starts with zero initial velocity and accelerates downward at g. The height fallen is h = (1/2)gt². Here the stone is simply dropped, so u = 0, and substituting g = 10 m/s² with t = 4 s gives h = (1/2) × 10 × 16 = 80 m. The option 40 m wrongly drops the factor of one-half twice or uses t = 4 with g halved improperly. The option 160 m results from forgetting the one-half factor entirely (10 × 16 = 160). The option 20 m comes from using t = 2 s instead of the given 4 s. Plausibility check: the final velocity on impact would be gt = 40 m/s, and the average velocity over the fall is 20 m/s, which across 4 s yields 80 m, matching our result and confirming the calculation is dimensionally and numerically sound.
This easy difficulty physics question is from the chapter kinematics, covering the topic of motion under gravity. It appeared in the 2025 exam.
Looking for more practice? Explore all physics questions or browse kinematics questions on RankGuru.