Physics 101/Fall 2013 HW3 Due Thu Feb 6 NAME Sect

Fill in the blank. (10 points)

1.) The force of air resistance on an object depends on the object’s ________________ and _____________.

2.) True / False When an object is falling at its terminal velocity, it is in equilibrium regarding its motion.

3.) The Action-Reaction Law is Newton’s (1st, 2nd, 3rd) ______________ Law.

4.) Action-reaction pairs (force pairs) are of the form F = F (see “Force Pairs” slide, chap 5)

The three conditions on a force pair are that they must be

a) ____________________________

b) ____________________________

c) ____________________________

d) Always on different objects

5.) When you kick a ball does the ball exert an equal and opposite force on your foot? (yes / no) __________________

6.) A ball is dropped from a great height (not free fall; air resistance is significant!)

Fill in the blank with increase(s), decrease(s), or stay(s) the same unless otherwise indicated.

a) As it falls through the air its speed _______________

b) causing the upward force of air resistance to____________________.

c) The net downward force ______________

d) and the magnitude of the acceleration_________________ as the ball continues to fall.

e) Eventually terminal velocity is reached; the force of air resistance is (greater than / less than / equal to)

________________ the force of gravity.

f) Velocity at this point _______________________________.

g) True / False Acceleration at terminal velocity = 0. _________________

7.) Fill in the blank with greater than / less than / equal to

A tiny little mosquito hits the windshield of your car.

The force acting on the mosquito is ____________________________the force acting on the

windshield. The effect of the force on the mosquito is ________________________ the effect of the force on the

windshield.

Fill in the Blank

8). The unit of work and energy is a __________________________ (N-M) which is also called a _________________________ .

9.) Work is a (scalar / vector) _____________quantity, therefore the sign (+ or – ) does not indicate a ___________________.

10.) When the net work done on an object is positive the object’s speed (increases / decreases) __________________________, and

when that work is negative the object’s speed (increases / decreases) ______________________________.

11.) True / False If force is applied without any motion, then the work done by the force is 0 N; i.e. there is no work done.

12.) True / False If the force applied to a moving object is perpendicular to its motion, maximum work will be done on the object.

13.) Kinetic energy is the energy of __________________________ and potential energy is _______________________energy.

14.) The change in kinetic energy or potential energy is equal to the _______________ done/accomplished.

=15.) A box is pulled 4 m horizontally across the floor by a 100 N force with components as shown (right). How much work is done by the pulling force?

__________________________________

16.) A box is being pulled 6 m across the floor by a 30-N force parallel to the floor as shown (right). The force of friction is 8 N.

a.) What is the work done by the pulling force. b.) What is the work done by the frictional force.

c.) What is the net work done on the box.

17.) Boxes A, B, C, and D have masses and velocities as shown. Determine how the Kinetic Energy of each box compares to that of box A.

________¿KEA _______¿KEA _______¿KEA

f30 N

80 N

60 N100 N

D

5v2m

C

4vm

B

v7m

A

vm