Centripetal force Transitional Reasoning Practice

Physics · Forces & Newton's Laws · Physics · Circular Motion & Gravitation

10 Physics practice questions on Centripetal force. Questions that build towards applied reasoning.

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Questions

  1. 1.

    A scientific satellite of mass mm orbits a planet of mass MM in a uniform circular orbit of radius rr at speed vv. Ground controllers maneuver the satellite into a new stable circular orbit of radius 4r4r. Which statement correctly describes how the gravitational centripetal force and the orbital speed of the satellite in the new orbit compare to their initial values?

    • A) The centripetal force decreases to 116\frac{1}{16} of its original value, and the orbital speed decreases to 12\frac{1}{2} of its original value.
    • B) The centripetal force decreases to 14\frac{1}{4} of its original value, and the orbital speed decreases to 12\frac{1}{2} of its original value.
    • C) The centripetal force decreases to 116\frac{1}{16} of its original value, and the orbital speed decreases to 14\frac{1}{4} of its original value.
    • D) The centripetal force decreases to 14\frac{1}{4} of its original value, and the orbital speed remains unchanged.
  2. 2.

    An aerospace engineer analyzes an airplane of mass mm executing a steady horizontal turn of radius RR at a constant speed vv. The airplane banks its wings at an angle θ\theta to the horizontal so that the aerodynamic lift force FLF_L, directed perpendicular to the wings, supports the airplane against gravity while providing the centripetal acceleration. Which component of the aerodynamic lift force acts as the centripetal force directed toward the center of the turn, and what is the resulting radius RR of the circle?

    • A) FLcos⁡θF_L \cos\theta acts as the centripetal force, and the radius is R=v2tan⁡θgR = \frac{v^2 \tan\theta}{g}.
    • B) FLcos⁡θF_L \cos\theta acts as the centripetal force, and the radius is R=v2gsin⁡θR = \frac{v^2}{g \sin\theta}.
    • C) FLsin⁡θF_L \sin\theta acts as the centripetal force, and the radius is R=v2gtan⁡θR = \frac{v^2}{g \tan\theta}.
    • D) FLsin⁡θF_L \sin\theta acts as the centripetal force, and the radius is R=gtan⁡θv2R = \frac{g \tan\theta}{v^2}.
  3. 3.

    To simulate Earth gravity during long-duration interplanetary travel, engineers design a large cylindrical habitat of radius RR that rotates at a constant rate in deep space. An astronaut of mass mm stands along the interior of the outer hull, oriented with their feet on the hull and head pointed toward the central rotation axis. Which force acts as the centripetal force to keep the astronaut moving in this circular path, and what tangential speed vv must the outer rim maintain to simulate an acceleration of magnitude gg?

    • A) The habitat's gravitational attraction provides the centripetal force, and the required speed is v=g/Rv = \sqrt{g/R}.
    • B) A fictitious centrifugal force directed inward provides the centripetal force, and the required speed is v=gRv = gR.
    • C) The normal force exerted inward by the hull floor provides the centripetal force, and the required speed is v=gRv = \sqrt{gR}.
    • D) The static friction force parallel to the hull floor provides the centripetal force, and the required speed is v=2gRv = \sqrt{2gR}.
  4. 4.

    In a laboratory experiment, a puck of mass m1m_1 moves on a frictionless horizontal tabletop in a circle of radius RR at a constant speed vv. A light string attached to the puck passes through a frictionless hole at the center of the table and supports a hanging block of mass m2m_2, which remains stationary. What is the magnitude of the centripetal force FcF_c acting on the puck, and what is the correct expression for its speed squared, v2v^2?

    • A) Fc=m1gF_c = m_1 g and v2=m1m2gRv^2 = \frac{m_1}{m_2} g R
    • B) Fc=m2gF_c = m_2 g and v2=m2m1gRv^2 = \frac{m_2}{m_1} g R
    • C) Fc=m2gF_c = m_2 g and v2=m1m2gRv^2 = \frac{m_1}{m_2} g R
    • D) Fc=(m1+m2)gF_c = (m_1 + m_2)g and v2=m2m1+m2gRv^2 = \frac{m_2}{m_1 + m_2} g R
  5. 5.

    An amusement park ride consists of a vertical hollow cylinder of radius RR rotating at a constant angular speed about its central axis. A rider of mass mm stands against the inner wall, and once the cylinder reaches a tangential speed vv, the floor drops away beneath the rider. If the rider remains held against the wall without sliding downward, which force provides the centripetal acceleration, and what is the minimum coefficient of static friction μs\mu_s between the rider and the wall to prevent slipping?

    • A) The static friction force directed vertically upward; μs=v2gR\mu_s = \frac{v^2}{g R}
    • B) The static friction force directed vertically upward; μs=gRv2\mu_s = \frac{g R}{v^2}
    • C) The normal force directed toward the rotation axis; μs=gRv2\mu_s = \frac{g R}{v^2}
    • D) The normal force directed toward the rotation axis; μs=v2gR\mu_s = \frac{v^2}{g R}
  6. 6.

    A civil engineer evaluates safety guidelines for vehicles traveling over a humpback bridge modeled as a vertical circular arc of radius RR. An automobile of mass mm crosses the highest point of the bridge at a constant speed vv while maintaining contact with the road. Which expression correctly gives the normal force FNF_N exerted by the road on the automobile at this peak, and what is the maximum speed vmaxv_{\text{max}} it can travel without becoming airborne?

    • A) FN=m(g+v2R)F_N = m\left(g + \frac{v^2}{R}\right) and vmax=gRv_{\text{max}} = \sqrt{gR}
    • B) FN=m(g−v2R)F_N = m\left(g - \frac{v^2}{R}\right) and vmax=gRv_{\text{max}} = \sqrt{gR}
    • C) FN=m(v2R−g)F_N = m\left(\frac{v^2}{R} - g\right) and vmax=2gRv_{\text{max}} = \sqrt{2gR}
    • D) FN=mgF_N = mg and vmax=gR2v_{\text{max}} = \frac{gR}{2}
  7. 7.

    A small bob of mass mm is attached to a fixed support by a light string and moves in a horizontal circle of radius rr at a constant speed vv. Throughout the motion, the string remains taut and maintains a constant angle θ\theta with the vertical. Neglecting air resistance, which option correctly identifies the source of the centripetal force and gives the correct expression for v2v^2?

    • A) The horizontal component of the string tension; v2=rgtan⁡θv^2 = rg \tan\theta
    • B) The horizontal component of the string tension; v2=rgsin⁡θv^2 = rg \sin\theta
    • C) The entire tension force acting along the string; v2=rgcos⁡θv^2 = rg \cos\theta
    • D) The net resultant of gravity and a fictitious outward force; v2=rgtan⁡θv^2 = \frac{rg}{\tan\theta}
  8. 8.

    A roller-coaster car of mass mm travels along a track and passes through the lowest point of a vertical circular dip of radius RR at speed vv. A force sensor beneath the wheels records the upward normal force exerted by the track on the car at this exact point. Which expression correctly gives the magnitude of the normal force, and what explains its relationship to the car's weight mgmg?

    • A) mg+mv2Rmg + \frac{m v^2}{R}, because the normal force must counteract gravity and supply the upward centripetal acceleration.
    • B) mv2R−mg\frac{m v^2}{R} - mg, because gravity acts in the same direction as the inward centripetal acceleration.
    • C) mv2R\frac{m v^2}{R}, because the centripetal force is a separate contact force that replaces the normal force at the dip.
    • D) (mg)2+(mv2R)2\sqrt{(mg)^2 + \left(\frac{m v^2}{R}\right)^2}, because the gravitational force and centripetal force act perpendicularly to each other.
  9. 9.

    A student investigates circular motion by placing two identical small blocks, PP and QQ, on a rough horizontal turntable that rotates at a constant angular speed. Block PP is placed at a distance rr from the central axis, while block QQ is placed at a distance 2r2r, and neither block slips relative to the surface. How does the magnitude of the net horizontal force acting on block QQ compare to that acting on block PP, and which force provides it?

    • A) It is twice as large for block QQ, provided by static friction directed toward the rotation axis.
    • B) It is four times as large for block QQ, provided by static friction directed toward the rotation axis.
    • C) It is half as large for block QQ, provided by kinetic friction directed opposite to the tangential motion.
    • D) It is equal for both blocks, provided by the normal force directed radially outward from the axis.
  10. 10.

    A test engineer investigates the lateral friction force acting on a vehicle of mass mm moving at a constant speed vv along a flat, horizontal circular track of radius rr. Under these baseline conditions, the vehicle completes the turn without skidding under a required horizontal centripetal force of magnitude FF. If a second vehicle of mass 2m2m travels at a speed of 2v2v along a track of radius 2r2r, what is the magnitude of the horizontal net force required to keep it on its circular path?

    • A) FF
    • B) 2F2F
    • C) 4F4F
    • D) 8F8F

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