Math Problem Statement

An object is launched vertically in the air at 24.5 meters per second from a 7-meter-tall platform. Using the projectile motion model h(t) = -4.9t^2 + v_0 t + h_0, where h(t) is the height of the projectile t seconds after its departure, v_0 is the initial velocity in meters per second, and h_0 is the initial height in meters, determine how long it will take for the object to reach its maximum height. What is the maximum height?

Solution

Let's analyze the given projectile motion equation:

h(t)=4.9t2+v0t+h0h(t) = -4.9t^2 + v_0 t + h_0

where:

  • v0=24.5v_0 = 24.5 m/s (initial velocity),
  • h0=7h_0 = 7 m (initial height),
  • Acceleration due to gravity is 9.8-9.8 m/s².

Step 1: Find Time to Reach Maximum Height

At maximum height, the velocity becomes zero. The velocity function is obtained by differentiating h(t)h(t):

v(t)=dhdt=9.8t+v0v(t) = \frac{dh}{dt} = -9.8t + v_0

Setting v(t)=0v(t) = 0:

0=9.8t+24.50 = -9.8t + 24.5

Solving for tt:

t=24.59.8=2.5 secondst = \frac{24.5}{9.8} = 2.5 \text{ seconds}

Step 2: Find Maximum Height

Substituting t=2.5t = 2.5 into the height equation:

h(2.5)=4.9(2.5)2+24.5(2.5)+7h(2.5) = -4.9(2.5)^2 + 24.5(2.5) + 7

=4.9(6.25)+24.5(2.5)+7= -4.9(6.25) + 24.5(2.5) + 7

=30.625+61.25+7= -30.625 + 61.25 + 7

=37.625 meters= 37.625 \text{ meters}

Final Answer:

  • Time to reach max height: 2.5 seconds
  • Maximum height: 37.625 meters

Would you like a breakdown of each calculation step?

Related Questions:

  1. What is the velocity of the object when it hits the ground?
  2. How long does it take for the object to hit the ground?
  3. What is the total flight time of the projectile?
  4. How would the maximum height change if the initial velocity were doubled?
  5. How does air resistance affect the motion of the projectile?

Tip: The maximum height in projectile motion depends only on the initial vertical velocity and gravity, not the object's mass.

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Math Problem Analysis

Mathematical Concepts

Projectile Motion
Kinematics
Calculus - Differentiation

Formulas

h(t) = -4.9t^2 + v_0 t + h_0 (Projectile Motion Equation)
v(t) = -9.8t + v_0 (Velocity as a function of time)

Theorems

Kinematic Equations for Uniformly Accelerated Motion
Maxima using First Derivative Test

Suitable Grade Level

Grades 10-12