A ball rises with speeds u/2, u/3 and u/4 at points A, B and C. If AB/BC=20/x, find x.
Physics · Mixed Chapter
JEE Main Practice

Question

A ball rises with speeds u/2, u/3 and u/4 at points A, B and C. If AB/BC=20/x, find x.

G1 Physics · Accepted Answer

Step 1: Use energy/vertical kinematics v²=u²−2gh for height difference. Step 2: AB=[(u/2)²−(u/3)²]/(2g) = (5u²)/(72g). Step 3: BC=[(u/3)²−(u/4)²]/(2g)=(7u²)/(288g). Step 4: AB/BC=(5/72)/(7/288)=20/7. Therefore x=7.