Question Details

The path followed by a body projected along y-axis is given as by y = √3x -(1 / 2)x² , if g = 10 m/s, then the initial velocity of projectile will be – (x and y are in m)

Options

A

3√(10) m/s

B

2√(10) m/s

C

10√(3) m/s

D

10√(2) m/s

Correct Answer :

2√(10) m/s

Solution :

The correct option is 2√(10) m/s.

Step-by-step Derivation:

The given equation of the path (trajectory) followed by the projectile is:

y=3x-12x2

The standard equation of the trajectory of a projectile projected with an initial velocity u at an angle θ with the horizontal (x-axis) is given by:

y=xtanθ-gx22u2cos2θ

By comparing the coefficients of x and x2 in the given equation and the standard equation, we get:

1) Comparing the coefficient of x:
tanθ=3
This gives the angle of projection:
θ=60°

2) Comparing the coefficient of x2:
g2u2cos2θ=12

Given the acceleration due to gravity g=10 m/s2 and θ=60°, we can substitute these values into the equation:

102u2cos2(60°)=12

Since cos(60°)=12, we have cos2(60°)=14. Substituting this value in:

102u2(14)=12

Simplifying the denominator on the left-hand side:

10(u22)=12

20u2=12

Cross-multiplying to solve for u2:

u2=40

Taking the square root on both sides:

u=40=4×10=210 m/s

Thus, the initial velocity of the projectile is 2√(10) m/s.

Unlock Our Free Library

Access expert-curated educational resources and study materials—completely free.

Discover more resources

You may also like

Mock Tests

View All
  • JEE
  • intermediate
  • 3 hours
  • chemistry, mathematics, physics

  • JEE
  • intermediate
  • 3 hours
  • chemical engineering, mathematics, physics