Question 1

An object slides down a frictionless ramp, tilted $$20^\circ$$ from the horizontal. The ramp is $$5$$ meters long. How fast is the object going at the bottom, assuming it started from rest at the top?

Accepted Answer

$$3.7$$ meters per second

Question 2

How long does it take for the object in the previous question to slide down the $$5$$ meter ramp?

Accepted Answer

$$2.0$$ seconds

Question 3

The moment of inertia for a solid sphere is $$0.4MR^2. $$What is the rotational kinetic energy of a solid sphere with a radius of $$50$$ centimeters, and a density of $$5$$ grams/cm$$^3$$, that is spinning at a rate of $$80$$ revolutions per minute?

Accepted Answer

$$8.57$$ Joules

Question 4

Which of the following forces exerts the most torque on a door about its hinge?

Accepted Answer

A $$10$$ Newton force applied at the edge of the door, pushing perpendicular to the direction the door swings

Question 5

Suppose you have a hollow sphere and a solid object, each with the same radius, mass, and rolling without slipping. Which will reach the bottom of a ramp first?

Accepted Answer

The solid object, because it has a smaller moment of inertia

Question 6

A spring with a spring constant of $$500 N/m is $$compressed until the stored energy is $$2,250$$ Joules. By how many meters is the spring compressed?

Accepted Answer

$$3$$ meters

Question 7

Two rocks of equal mass collide and bounce off one another. The initial velocities were $$1$$ meter per second and $$7$$ meters per second, both in the same direction. Following the collision, which of the following is a possible set of values for the two rocks? (Assume the collision is elastic and momentum is conserved.)

Accepted Answer

4 meters per second and 4 meters per second

Question 8

What is the acceleration of an object sliding down a ramp angled $$60^\circ$$ with respect to horizontal if the coefficient of sliding friction between the object and the ramp is $$0.3$$?

Accepted Answer

$$6.1 m/s$^2$$

Question 9

Which of the following objects has the most angular momentum?

Accepted Answer

A hollow sphere with radius $$0.5$$ meters, and a density of $$4$$ grams/cm$$^3$$, rotating at $$60$$ revolutions/minute

Question 10

Which of the following objects has the most kinetic energy associated with their rotation?

Accepted Answer

A hollow sphere with radius $$0.5$$ meters, and a density of $$4$$ grams/cm$$^3$$, rotating at $$60$$ revolutions/minute

Question 11

Suppose you walk two miles north, one mile east, and then $$1.5$$ miles in a direction $$15^\circ$$ south of due west. Where are you relative to your starting point?

Accepted Answer

$$0.2$$ miles north and $$1.3$$ miles east

Question 12

Suppose you drive around a flat circular track with radius $$20$$ meters. If you drive at a constant speed of $$10$$ meters per second, what is the minimum coefficient of friction required between your tires and the road to prevent skidding?

Accepted Answer

The coefficient of static friction between my tires and the road is greater than $$0.5$$

Question 13

Suppose two weights are attached to a massless frictionless pulley as shown in the diagram. One weight is $$20 kg $$and the other is $$10 kg. $$What is the magnitude of the acceleration of the $$20 kg $$weight?

Accepted Answer

$$3.3 m/s$^2$$

Question 14

If the pulley in the previous question is not massless, how would this affect the acceleration of the $$20 kg $$weight?

Accepted Answer

It would decrease

Question 15

Which of the following spheres would have the largest terminal velocity? Assume that the Reynolds number of the air flow around the balls is very high in each case, so the drag is proportional to the square of the velocity.

Accepted Answer

A ball that is $$2$$ meters in diameter, and weighs $$1000$$ kilograms

Question 16

A $$10 kg $$mass is simultaneously acted upon by a $$3 N $$force directed eastward, and a $$4 N $$force directed northward. What is the magnitude of the resulting acceleration?

Accepted Answer

$$0.7 m/s$^2$$

Question 17

You are stranded in space, $$50$$ meters from your spaceship. All you have is an apple, weighing $$0.2 kg. To $$get back to the spaceship, you throw the apple. What best describes your motion?

Accepted Answer

You move in the opposite direction to the apple, with a speed determined by conservation of momentum

Question 18

Suppose you throw an apple with mass $$0.2 kg at$$ $$20 m/s to $$propel yourself back to your spaceship. Your mass is $$100 kg. $$What is your resulting velocity?

Accepted Answer

$$0.04 m/s$

Question 19

When you apply the brakes on a bicycle, you are exerting a torque on the wheel. If the mass of the wheel is set to zero, what is the net torque on the wheel?

Accepted Answer

The net torque is zero

Physics 1403 Practice Final: Study Notes on Motion, Forces, Energy, Rotation, and Friction

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