The questions and problems are in the following sections:

  Inertia              (answers to this section)           (back to the top)

1.  Describe the concept of INERTIA.

2.  If you stand on the middle of a jump rope and pull up on the ends you cannot lift yourself
     off of the floor.  Why not?

3. Two forces, equal in magnitude, are applied to an object in two
     different combinations as shown at the right.  Will either
     situation result in accelerating the object?
 
 
 
 

4.  An object moving horizontally across a table is observed slowing down.
         a) Is there a non-zero total force acting on the object?

         b) Is the force of gravity directly involved with the object’s slowing down?  Explain.
 

5.  A car rounds a curve with constant speed.
         a) Is the car accelerating?

         b) Is the car experiencing a total, non-zero force from the outside?
             If so, where does the force come from?
 

6.  If a car travels along a straight road at a constant speed is it experiencing a non-zero total force?

7.  Why do your books slide off of the seat of your car when you make a sudden stop?

8.  Explain how the law of inertia applies to an airline passenger drinking a glass of soda when
     the plane suddenly drops 10 m vertically.

9.  Whiplash is the most common injury in a rear end collision. Is the head of a person being
     rear ended actually thrown back during the collision?
 

 Action / Reaction Forces        (answers to this section)              (back to the top)

1.  Identify the action/reaction forces in the following situations:

 a) you kick a ball with your foot.
 b) the space shuttle lifts off the launch pad
 c) the force of gravity
 d) you jump straight into the air

2.  The engine of a car is internal to the car and therefore cannot push directly on the
     car to accelerate it.

 a) What external force on the car is actually responsible for its acceleration?
 b) What are the action/reaction forces in making the car accelerate?

3.  A large, loaded truck rear ends a stationary compact car.

 a)  Does the car experience a larger force during the collision than the truck?
 b)  Explain, using one of Newton’s laws, why a passenger in the car is more likely
      to be injured than someone in the truck

4.  According to Newton’s Third Law, when you push on a grocery cart the cart pushes back
     on you with an equal amount of force.  How is it possible for you to move the cart forward?

5.  Could a sailboat be moved forward by setting a large fan on the deck and blowing it on the sail?
     Explain.

6.  Use Newton’s laws to explain the reason for each of the following statements, indicating
     which of the laws best applies.

 a) It takes longer for a car to accelerate when it has five passengers in it than just one.
 b) Many a novice hunter has experienced a sore shoulder after firing a shotgun.
 c) Buses provide poles and overhead rails for standing passengers to hold.

Newton's Second Law                   (answers to this section)    (back to the top)

1. If the same total force is applied to the two objects at the right,
     will they have the same acceleration?  Explain.
 
 
 
 

2.  If the two objects in # 1 are given the same acceleration, are they experiencing the same
     total force?  Explain.

3.Two blocks with the same mass are connected by a string and are
     being pulled along the surface by a constant force larger than the
     frictional force.

 a) Will the two blocks move with constant velocity?
 b) Will the two blocks move with the same motion?
 c) Will the tension in the connecting string be greater
     than, equal to, or less than the pulling force?

4. Two equal masses, connected by a string, are placed on a

 a) Will the system accelerate?
 b) Will the tension in the string be greater than, equal to,
     or less than the weight of either mass?
 c) If the left mass is doubled in size, will the system move
     with constant velocity?

6.  A 30.0 g arrow is accelerated by a bowstring at 7000. m/s2 .  What is the total force
     acting on the arrow?

7.  A 4.0 Kg box is pulled across the table by a horizontal force of 30.0 N.  If the frictional
     force on the box is 10.0 N, what is the acceleration of the box?

8.  What is the weight of a 2.5 Kg mass?

9.  An upward force of 35.0 N is applied to a 2.0 Kg ball.

 a)  What is the total force on the ball?
 b) What is the acceleration of the ball?

Newton's Laws and Motion                    (answers to this section)    (back to the top)

1.  A 1.5 Kg croquet ball rolls in the grass where the force of friction is 12.0 N.
    If the ball initially moves at 10 m/sec, how far will the ball travel before stopping?

2.  A 150 g tennis ball is in contact with the racket for 0.75 s during a serve.  If the ball
     leaves the racket at 45 m/s, what is the total force on the ball?

3.  A 10,000 Kg airplane accelerates along a runway from rest to reach a speed of 55 m/s
     in 500 m.  If the average frictional force on the plane is 10,000 N, what thrust is required
     of the engines?

4.  A 4.3 Kg watermelon is dropped from a second floor window 15 m above the ground.
     If the air resistance on the melon averages 12 N, what is the speed of the melon when
     it hits the ground?

5. An Atwood’s machine is set up with two masses of 500 g and 300 g.
     How long will it take the system to move 0.4 m, starting from rest?
 
 
   

Uniform Circular Motion      (answers to this section)    (back to the top)

1.  Two identical cars are traveling around a curve in the road .  If car A is moving at twice
     the speed as car B, which car experiences the larger acceleration?

2.  Two identical cars are traveling at the same speed around two different curves.  If Car A
     goes around a curve of larger radius, which car has the larger acceleration?

3.  What is the frequency of the tip of the second hand on a clock in hertz?

4.  When  an object goes around a circular path at constant speed, what is the direction of the
     total force on the object?

5.  You are in the passenger seat of a car when it makes a left hand turn going too fast.

 a) What do you feel?
 b) Is there a force pushing you toward the door?
 c) What is the direction of the total force on you while you are going around the
     corner?
 d) Look at the diagram at the right.  If the door were to open,
     which path would best describe your motion?
     (before you hit the ground and get all scraped up)

6.  What factors would determine the maximum speed a car can go around a curve?

7.  If a ball is swung in a vertical circle at a constant speed, at what point on the path, if any,
     is the tension in the string the greatest?

8.  A hot wheels car travels at a constant speed of 1.5 m/s around a horizontal curve with a
     radius of 0.65 m.  What is the centripetal acceleration of the car?

9.  A circus elephant (1500. Kg) is running around the center ring (20. m radius) at a constant
     speed of 5.0 m/s.

 a) What is the centripetal acceleration of the elephant?
 b) How much force is needed to make the elephant accomplish this trick?
 c) What provides the force on the elephant?
 d) Why isn’t it a good idea to do this trick in the Ice Capades?

10.  A Ferris wheel with a radius of 30.0 m makes one complete revolution in 20.0 s.

 a) What is the linear speed of a rider on the wheel?
 b)  What is the magnitude of the centripetal acceleration of a rider?
 c) Do different sized riders experience different accelerations?
 d) What is the centripetal force needed to keep a 55 Kg rider going in the circle?
 e)  What is the Normal force felt by the 55 Kg rider:

  i) at the top of the ride?
  ii) at the bottom of the ride?

11. The top of the first loop in the Demon at Great America has a radius of 5.0 m.
      If the train goes through that portion of the ride at 9.1 m/s,

 a) what is the acceleration of a rider at the top of the loop?
 b) What is the amount of Normal force felt by a 60 Kg rider at the top of the loop?
 c) Does the rider need a shoulder harness to keep them in the seat at this point?
 d) Would a larger rider feel

  i)  the same amount of force?
  ii)  proportionately the same gut wrenching, scream inducing force?