AP PHYSICS B Midterm Review

Fill in what the following variables stand for and the metric units for each.

Variables

units

 

 

What is “g”? 

 

What is it equal to?

d

 

t

 

v

 

a

 

m

 

F

 

 

What is “G”?

 

What is it equal to?

W

 

P

 

KE

 

PEg

 

PEe

 

h

 

 

k

 

 

What is µ?

 

What does it tell you?

x

 

p

 

r

 

T

 

f

 

 

Formulas

Accelerated motion:

 

Arthur:

 

Vickie:

 

Dickie:

 

What is true about acceleration when velocity is constant? 

 

What would dickie look like when velocity is constant?

 

Vectors:

 

Pythagorean:

Sohcahtoa:

 

 

 

How do these formulas change if you are solving for the angle?

 

 

 

Quadratic equation:

 

Force

Newton’s 2nd law:

Weight:

Universal Gravitation:

 

Friction:

Force of gravity down a slope:

 

Force of friction along a slope:

 

Normal force along a slope:

 

Circular Motion

Centripetal force:

 

Centripetal acceleration:

 

Circular velocity:

 

What keeps a car from sliding as it goes along a curve on a flat road?

How is this related to the net force acting on the car?

 

Write out the formula for the car going along a curve.

 

Work, Power, Energy

Work:

 

Power:

 

Gravitational potential energy:

 

Elastic potential energy:

 

Kinetic energy:

 

 

Momentum

Momentum:

 

Impulse/change of momentum

 

Conversation of momentum

   Explosive:

 

   Inelastic:

 

   Elastic:

 

Conceptual

1.  What is the difference between speed and velocity?

 

2.  What is the difference between velocity and acceleration?

 

3.  What is the difference between scalar and vector quantities?  Know examples of each.

 

4.  What are the conditions necessary for “freefall”?

 

5.  Know Newton’s 3 laws (what is inertia and its significance, relationship between force, mass and acceleration, interactions between objects exerting forces)

 

6.  What does net force refer to?

 

7.  What is the difference between weight and mass?  What are the units of each?  How do you calculate weight?

 

8.  What is a normal force?  Is it always the same as an object’s weight?  Why or why not?

 

9.  What is friction?  How is it related to the motion of an object?

 

10.  If you are adding vectors. What must be true about the units involved?

 

11.  Newton didn’t discover gravity, but rather something about gravity.  What was it that Newton realized about gravity? (Hint:  What is the connection he made between an apple and the moon?)  Explain.

 

12.  If an object in orbit (circular motion) is traveling at a constant speed, how can it be accelerating?

 

13.  What direction is the force acting that is causing this acceleration?

 

14.  When traveling in a circle (or simply turning), why does it feel like you are being pushed or pulled outward?

 

15.  When on a slope, what makes the object slide down the slope?

 

16.  What prevents the object from sliding?

 

17.  Do the forces of friction and gravity ever act in the same direction along a slope?  If so, when?

 

 

Practice Problems

1.  How far can a cyclist travel in 2.5h along a straight road if her average velocity is 18 km/h? (45 km)

2.  In coming to a stop, a car leaves skid marks 80 m long on the highway.  Assuming a deceleration of 7m/s2, estimate the speed of the car just before braking.  (33m/s)

3.  A stone is thrown vertically upward with a speed of 12m/s from the edge of a cliff 70m high.

            a)  How much later does it reach the bottom of the cliff? (5.33s)

            b)  What is its speed just before hitting? (40.2m/s)

            c)  What total distance did it travel? (89.7 m)

4.  What average force is needed to accelerate a 7g pellet from rest to 175 m/s over a distance of .7m along the barrel of a rifle? (153N)

5.  What is the weight of a 76 kg astronaut

            a) on Earth?

            b) on the Moon (g= 1.7 m/s2)

6.  A projectile is fired with an initial speed of 75.2 m/s at an angle of 34.5˚ above the horizontal on a long flat firing range.  Determine

            a) the maximum height reached by the projectile (92.6m)

            b) the total time in the air (8.69s)

            c)  the total horizontal distance covered (the range), (539m)

            d) the velocity of the projectile 1.5s after firing. (68 m/s, 24.2˚ above the horizontal)

7.  The cliff divers of Acapulco push off horizontally from rock platforms about 35m above the water, but they must clear rocky outcrops at water level that extend out into the water 5m from the base of the cliff directly under their launch point.  What minimum pushoff speed is necessary to clear the rocks?  How long are they in the air? (t = 2.7s, v = 1.9 m/s)

8.  A box is given a push so that it slides across the floor.  How far will it go, given that the coefficient of kinetic friction is 0.2 and the push imparts an initial speed of 4 m/s? (4.1m)

9.  A carton lies on a slope tilted at the angle of 22.0˚  to the horizontal, with µk = 0.12. 

            a)  Determine the acceleration of the carton as it slides down the slope. (3.67 m/s2)

            b)  If the carton starts from rest 9.1m up the plane from the base, what will be the carton’s speed when it reaches the bottom of the incline? (8.17m/s)

10.  Suppose the space shuttle is in orbit 400 km from the Earth’s surface, and circles the Earth about once every 90 minutes.  Find the centripetal acceleration of the space shuttle in its orbit. (8.82 m/s2)

11.  A 1200 kg car rounds a curve of radius 67 m.  If the car is traveling at 95 km/h, what frictional force is acting on the car to make the turn?  What is the minimum coefficient of friction needed for this turn?

12.  Two masses hang on opposite sides of a pulley system.  Mass A (25 kg) is at rest 8 m above the ground.  Mass B is 10 kg. 

            a)  How fast will mass A be going when it reaches the ground?

            b)  What is the tension in the rope holding up mass B?

 

Work, Energy, Power, Momentum

 

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