A ball is thrown from a roof with a speed of 10.0 m/s and an angle of 37.0° with respect to the

horizontal. What are the vertical and horizontal components of the ball’s displacement 2.5 s after it is
thrown?

1 answer

To find the vertical and horizontal components of the ball’s displacement 2.5 seconds after it is thrown, we can use the initial speed and angle to determine the components of the velocity and then use kinematic equations.

Step 1: Resolve the initial velocity into components

The initial speed (\(v_0\)) is 10.0 m/s, and the angle (\(\theta\)) is 37.0°.

Horizontal component of velocity (\(v_{0x}\)): \[ v_{0x} = v_0 \cdot \cos(\theta) = 10.0 \cdot \cos(37.0^\circ) \] Calculating \(\cos(37.0^\circ)\): \[ \cos(37.0^\circ) \approx 0.7986 \] Now calculate \(v_{0x}\): \[ v_{0x} \approx 10.0 \cdot 0.7986 \approx 7.986 , \text{m/s} \]

Vertical component of velocity (\(v_{0y}\)): \[ v_{0y} = v_0 \cdot \sin(\theta) = 10.0 \cdot \sin(37.0^\circ) \] Calculating \(\sin(37.0^\circ)\): \[ \sin(37.0^\circ) \approx 0.6018 \] Now calculate \(v_{0y}\): \[ v_{0y} \approx 10.0 \cdot 0.6018 \approx 6.018 , \text{m/s} \]

Step 2: Horizontal displacement

The horizontal displacement (\(x\)) after time \(t\) can be calculated using: \[ x = v_{0x} \cdot t \] Substituting in the values: \[ x = 7.986 \cdot 2.5 \approx 19.965 , \text{m} \]

Step 3: Vertical displacement

The vertical displacement (\(y\)) can be calculated using the following kinematic equation, considering the effect of gravity (\(g = 9.81 , \text{m/s}^2\)): \[ y = v_{0y} \cdot t - \frac{1}{2} g t^2 \] Substituting in the values: \[ y = 6.018 \cdot 2.5 - \frac{1}{2} \cdot 9.81 \cdot (2.5)^2 \] Calculating: \[ y = 15.045 - \frac{1}{2} \cdot 9.81 \cdot 6.25 \] \[ y = 15.045 - 30.67125 \approx -15.62625 , \text{m} \]

Conclusion

After 2.5 seconds, the vertical and horizontal components of the ball’s displacement are approximately:

  • Horizontal Displacement (\(x\)): \(19.97 , \text{m}\)
  • Vertical Displacement (\(y\)): \(-15.63 , \text{m}\)

This indicates that the ball has fallen approximately 15.63 meters below its original height.