Math Problem Statement

When s = 0 the spring is in its unstretched position. The mass of the ball is 0.35 kg. If the spring is pulled back 125 mm and released to strike the ball, calculate the velocity of the ball and the normal force when the angle is θ = 52°. Ignore rotational kinetic energy.

Solution

Let's break down the problem and solve it step by step.

Given:

  • Mass of the ball: m=0.35kgm = 0.35 \, \text{kg}
  • Spring constant: k=1500N/mk = 1500 \, \text{N/m}
  • Spring displacement: s=125mm=0.125ms = 125 \, \text{mm} = 0.125 \, \text{m}
  • Radius of the track: r=1.5mr = 1.5 \, \text{m}
  • Angle θ=52\theta = 52^\circ
  • Neglect rotational kinetic energy (only translational kinetic energy is considered).

Part 1: Velocity of the ball [v][v]

The spring's potential energy is converted into the kinetic energy and the gravitational potential energy of the ball.

Energy conservation equation:

The total mechanical energy is conserved between the compressed spring and the position where the ball is at angle θ=52\theta = 52^\circ.

The energy stored in the spring: Espring=12ks2E_{\text{spring}} = \frac{1}{2} k s^2

The total energy at the angle θ\theta: Etotal=K+UgE_{\text{total}} = K + U_g where:

  • K=12mv2K = \frac{1}{2} m v^2 is the kinetic energy,
  • Ug=mghU_g = mgh is the gravitational potential energy, where h=r(1cosθ)h = r(1 - \cos \theta).

Thus, applying conservation of mechanical energy: 12ks2=12mv2+mgh\frac{1}{2} k s^2 = \frac{1}{2} m v^2 + mgh

Substitute h=r(1cosθ)h = r(1 - \cos \theta) into the equation: 12ks2=12mv2+mgr(1cosθ)\frac{1}{2} k s^2 = \frac{1}{2} m v^2 + mg r(1 - \cos \theta)

Now solve for vv: v=ks2m2gr(1cosθ)v = \sqrt{\frac{k s^2}{m} - 2g r(1 - \cos \theta)}

Substitute the given values:

  • k=1500N/mk = 1500 \, \text{N/m}
  • s=0.125ms = 0.125 \, \text{m}
  • m=0.35kgm = 0.35 \, \text{kg}
  • r=1.5mr = 1.5 \, \text{m}
  • g=9.81m/s2g = 9.81 \, \text{m/s}^2
  • θ=52\theta = 52^\circ

First, calculate cos(52)\cos(52^\circ): cos(52)0.6157\cos(52^\circ) \approx 0.6157

Now, calculate the height: h=1.5(10.6157)1.5×0.3843=0.5765mh = 1.5(1 - 0.6157) \approx 1.5 \times 0.3843 = 0.5765 \, \text{m}

Plug everything into the velocity equation: v=1500×(0.125)20.352×9.81×1.5×0.3843v = \sqrt{\frac{1500 \times (0.125)^2}{0.35} - 2 \times 9.81 \times 1.5 \times 0.3843}

Part 2: Normal force between the ball and the track [N][N]

The normal force can be found using the following equation for a body moving in a circular path: N=m(v2r)+mgcosθN = m \left( \frac{v^2}{r} \right) + mg \cos \theta

Where v2r\frac{v^2}{r} represents the centripetal acceleration, and mgcosθmg \cos \theta is the component of gravitational force acting perpendicular to the track.

Substitute the known values of mm, vv, rr, and θ\theta into the above equation.

Conclusion

Let me calculate the exact values for velocity and normal force. I'll continue by computing these values, and then provide the results.

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Math Problem Analysis

Mathematical Concepts

Energy Conservation
Kinematics
Circular Motion
Potential Energy
Kinetic Energy

Formulas

E_spring = 0.5 * k * s^2
K = 0.5 * m * v^2
U_g = m * g * h
v = sqrt((k * s^2 / m) - 2 * g * r * (1 - cos(θ)))
N = m * (v^2 / r) + m * g * cos(θ)

Theorems

Conservation of Mechanical Energy
Newton's Second Law for Circular Motion

Suitable Grade Level

Grades 11-12 (Physics)