Question 1

A small rocket is launched straight up with a constant thrust of 1500 N and experiences a constant horizontal wind force of 20 N. Neglecting air resistance and mass loss, what is the shape of the rocket's trajectory during the first 1.0 km of flight?

Accepted Answer

A straight line at an angle, because both vertical and horizontal accelerations are constant.

Question 2

A projectile is launched with initial speed $$v_0 at an $$angle $$	heta$$ above the horizontal. Neglecting air resistance, at what angle $$	heta is $$the range maximized?

Accepted Answer

$$	heta = 45^\circ$$

Question 3

A car of mass $$m$$ moves around a flat curve of radius $$r at $$maximum speed without sliding. If the coefficient of static friction between the tires and the road is $$\mu_s$$, what is the maximum speed $$v_{max}$$ the car can have?

Accepted Answer

$$v_{max} = \sqrt{\mu_s g r}$$

Question 4

A hockey puck is tied to a stake in the ice and swung in a circle. What force produces the centripetal acceleration of the puck?

Accepted Answer

Tension in the string

Question 5

A car moves around a circular track at constant speed $$v. If $$the speed doubles, how does the centripetal acceleration change?

Accepted Answer

It quadruples.

Question 6

A roller coaster car of mass $$m$$ goes around a vertical loop of radius $$r. $$What is the minimum speed $$v_{min} at $$the top of the loop so that the car does not fall off?

Accepted Answer

$$v_{min} = \sqrt{g r}$$

Question 7

A satellite orbits the Earth in a low circular orbit of radius $$r. $$What is the required orbital speed $$v$$ for the satellite, neglecting air resistance?

Accepted Answer

$$v = \sqrt{g r}$$

Question 8

A car is moving around a banked curve of radius $$r at $$the exact speed $$v = \sqrt{g r 	an 	heta}. $$What force provides the required centripetal acceleration?

Accepted Answer

The radial component of the normal force only.

Question 9

A coin sits on a turntable rotating at constant angular velocity. What is the direction of the net force acting on the coin?

Accepted Answer

Radially inward toward the center.

Question 10

A pendulum swings back and forth. When the bob is at the lowest point and moving fastest, what is the direction of the net force acting on it?

Accepted Answer

Upward, toward the pivot.

Question 11

A car coasts over the top of a hill at constant speed. What is the direction of the net force acting on the car at the very top?

Accepted Answer

Downward, toward the center of the circular path.

Question 12

Which of the following statements about the 'centrifugal force' is correct?

Accepted Answer

It is a fictitious force that appears in a rotating (non-inertial) reference frame.

Question 13

A car is moving around a banked curve at a speed lower than $$v = \sqrt{g r 	an 	heta}. $$What role does static friction play?

Accepted Answer

It points uphill, preventing the car from sliding down the incline.

Question 14

A roller coaster car is at the bottom of a vertical loop. How does the normal force on the car compare to its weight?

Accepted Answer

The normal force is greater than the weight.

Question 15

Which of the following is true about the acceleration of a particle in uniform circular motion?

Accepted Answer

It is purely radial, pointing toward the center of the circle.

Question 16

A satellite in low Earth orbit is said to be 'weightless.' What is the best explanation for this phenomenon?

Accepted Answer

The satellite is in free fall, constantly falling toward Earth but never hitting it.

Question 17

A car is moving around a banked curve at a speed higher than $$v = \sqrt{g r 	an 	heta}. $$What role does static friction play?

Accepted Answer

It points downhill, preventing the car from sliding up the incline.

Question 18

Which of the following is NOT a step in the recommended problem-solving strategy for two-dimensional dynamics?

Accepted Answer

Ignore the direction of forces and accelerations.

Question 19

A projectile is launched horizontally from a tower of height $$h on a $$spherical, airless planet. What path does it follow if its speed is sufficiently large?

Accepted Answer

It enters a circular orbit around the planet.

Dynamics II: Motion in a Plane – Study Notes

Study Guide - Practice Questions

Study Guide - Flashcards