Two bicycles start at the same time from points P and Q, moving toward each other. If the distance between P and Q is 120 km and their speeds are 12 km/h and 8 km/h respectively then after how much time will they meet each other?
A
6 hours
B
5.5 hours
C
6.5 hours
D
7 hours
উত্তরের বিবরণ
Question: Two bicycles start at the same time from points P and Q, moving toward each other. If the distance between P and Q is 120 km and their speeds are 12 km/h and 8 km/h respectively then after how much time will they meet each other?
Solution:
Given,
The distance between P and Q = 120 km
Speed of 1st bicycle = 12 km/h
Speed of 2nd bicycle = 8 km/h
The bicycles are moving toward each other,
So their relative speed = (Speed of 1st bicycle + Speed of 2nd bicycle)
= (12 + 8) km/h
= 20 km/h
Time = (Distance ÷ relative speed)
= (120 ÷ 20)
= 6 h
0
Updated: 2 weeks ago
একটি নৌকা স্রোতের অনুকূলে ঘণ্টায় ১৫ কি.মি. এবং প্রতিকূলে ঘণ্টায় ৯ কি.মি. যায়। স্রোতের বেগ কত?
Created: 1 week ago
A
২ কি.মি./ঘণ্টা
B
৩ কি.মি./ঘণ্টা
C
৪ কি.মি./ঘণ্টা
D
৬ কি.মি./ঘণ্টা
প্রশ্ন: একটি নৌকা স্রোতের অনুকূলে ঘণ্টায় ১৫ কি.মি. এবং প্রতিকূলে ঘণ্টায় ৯ কি.মি. যায়। স্রোতের বেগ কত?
সমাধান:
আমরা জানি,
স্রোতের বেগ = (স্রোতের অনুকূলে নৌকার গতি − স্রোতের প্রতিকূলে নৌকার গতি)/২
= (১৫ - ৯)/২
= ৬/২
= ৩
অর্থাৎ স্রোতের বেগ = ৩ কি.মি./ঘণ্টা
0
Updated: 1 week ago
A man rows downstream at 32 km/h and rows upstream at 22 km/h. At what speed can he row in still water?
Created: 2 weeks ago
A
27 km/h
B
5 km/h
C
54 km/h
D
15 km/h
Question: A man rows downstream at 32 km/h and rows upstream at 22 km/h. At what speed can he row in still water?
Solution:
Given,
Man rows downstream = 32 km/h
Man rows upstream = 22 km/h
We know that,
Speed in still water = (Downstream speed + Upstream speed) ÷ 2
= (32 + 22) ÷ 2
= 54 ÷ 2
= 27 km/h
0
Updated: 2 weeks ago
Two pipes P and Q can fill a cistern in 15 and 20 minutes respectively. Both pipes are opened together, after how many minutes should Q be turned off, so that the cistern be fill in 12 minutes?
Created: 2 weeks ago
A
9 minutes
B
6 minutes
C
4 minutes
D
8 minutes
Question: Two pipes P and Q can fill a cistern in 15 and 20 minutes respectively. Both pipes are opened together, after how many minutes should Q be turned off, so that the cistern be fill in 12 minutes?
Solution:
P can fill the cistern in 15 minutes
So in 1 min P can fill the cistern = 1/15 th part
In 12 min, P can fill the cistern = 12/15
= 4/5 part
Remaining part = 1- (4/5) part
= 1/5 part
As Q can fill full cistern in 20 minutes
So it will fill 1/5 part in = (1/5) × 20 = 4 minutes.
∴ Pipe Q should be turned off after 4 minutes.
0
Updated: 2 weeks ago
