Question

Difficulty: EasyProjectile Motion

An object is projected from level ground with an initial speed of 30 m/s30\text{ m/s} at an angle of 3030^\circ to the horizontal. Taking the acceleration due to gravity g=10 m/s2g = 10\text{ m/s}^2, calculate the maximum height reached by the object in meters.

Answer: 11.25 m

Answer

The maximum height reached by the object is 11.25 m11.25\text{ m}.
The vertical component of initial velocity is uy=30sin(30)=15 m/su_y = 30 \sin(30^\circ) = 15\text{ m/s}. At maximum height, vertical velocity becomes zero, so H=uy22g=15220=11.25 mH = \frac{u_y^2}{2g} = \frac{15^2}{20} = 11.25\text{ m}.

Step-by-Step Solution

1
Calculate the vertical component of the initial velocity.
uy=usinθ=30×sin(30)=15 m/su_y = u \sin\theta = 30 \times \sin(30^\circ) = 15\text{ m/s}
Only the vertical component of initial velocity determines the maximum height.
2
Apply the vertical motion equation at maximum height where vertical velocity is zero.
H=uy22g=1522×10=11.25 mH = \frac{u_y^2}{2g} = \frac{15^2}{2 \times 10} = 11.25\text{ m}
Using vy2=uy22gHv_y^2 = u_y^2 - 2gH with vy=0v_y = 0 gives H=uy22gH = \frac{u_y^2}{2g}.

Key Concept

Maximum height of a projectile
Estimated Time:45s
Rate this question