Question

A body is projected up a smooth inclined plane with velocity v from the point A as shown in the figure. The angle of inclination is 45⁰ and the top is connected to a well of diameter 40 m. If the body just manages to cross the well, what is the value of v ? Length of inclined plane is $20\sqrt{2}$m.

• A. 40 ms^–1
• B. $40\sqrt{2}$ms^–1
• C. 20 ms^–1
• D. $20\sqrt{2}$ms^–1

Answer 1

Answer: (D)

$20\sqrt{2}$ms^–1

Answer 2

$\frac { \mathrm { v } ^ { \prime 2 } } { \mathrm {~g} }$ = 40 [Q q = 45⁰] v'² = 40 g but v'² = v² – 2al

or 40g = v² – 2 (g sin 45⁰). $20 \sqrt { 2 }$ or 40 g = v² – 40g

or v² = 80g or v = $20 \sqrt { 2 }$ m/s