wiz-icon
MyQuestionIcon
MyQuestionIcon
2
You visited us 2 times! Enjoying our articles? Unlock Full Access!
Question

A body is thrown vertically upward from the top A of tower. It reaches the ground in t1 s. If it is thrown vertically downwards from A with the same speed it reaches the ground in t2 s. If it is allowed to fall freely from A, then the time it takes to reach the ground is given by

A
t=t1+t22
No worries! We‘ve got your back. Try BYJU‘S free classes today!
B
t=t1t22
No worries! We‘ve got your back. Try BYJU‘S free classes today!
C
t=t1t2
Right on! Give the BNAT exam to get a 100% scholarship for BYJUS courses
D
t=t1t2
No worries! We‘ve got your back. Try BYJU‘S free classes today!
Open in App
Solution

The correct option is C t=t1t2
Taking downward direction as positive direction.
Case 1: Ball is thrown upwards with velocity u.
Using second equation of motion we get
+h=ut1+12gt21(i)
Case 2: Ball is thrown downwards with velocity u.
Using second equation of motion we get
+h=ut2+12gt22(ii)
Multiplying Eq. (i) by t2 and Eq. (ii) by t1 and adding. We get
h(t1+t2)=12gt1t2(t1+t2)
or h=12gt1t2(iii)
In case of free fall, we can write
h=12gt2(iv)
t2=t1t2
t=t1t2

flag
Suggest Corrections
thumbs-up
1
similar_icon
Similar questions
View More
Join BYJU'S Learning Program
similar_icon
Related Videos
thumbnail
lock
Free Fall
PHYSICS
Watch in App
Join BYJU'S Learning Program
CrossIcon