1-D MotionWSHS Physics

Vectors vs. ScalarsVector- a quantity having direction as well as magnitude

Scalar- a quantity having magnitude only

Distance vs Displacement

Avg Speed vs. Avg Velocity

What’s the difference?

Average speed is defined as total

distance traveled over the duration

of travel.

Scalar quantity

Average velocity is defined as

displacement over the duration of

travel.

Vector quantity

Instantaneous Speed and VelocityInstantaneous speed- the speed of an object at a moment in time

Instantaneous velocity- the velocity of an object at a moment in time

AccelerationAcceleration- changing of an object’s velocity with time

● Defined as the change in velocity over the change in time

● Vector quantity

● Dimensions of length per time squared, commonly has units m/s

2

Instantaneous AccelerationThe acceleration of an object at a point in time is the object’s instantaneous

acceleration.

1D Motion w/ Constant Velocity

1D Motion w/ Constant Acceleration

The Big FourThe basic equations of kinematics

Used to describe the motion of an object with constant acceleration

Free Fallg = 9.8 m/s

2

Approximate value: 10 m/s

2

Vertical ProjectileWhen an object is thrown straight up in the air and follows a linear path

College Physics (AP Edition) p. 35 #14You have two small metal balls. You drop the first ball and throw the other one in the

downward direction. Choose the statements that are not correct.

(a) The second ball will spend less time in flight.

(b) The first ball will have a slower final speed when it reaches the ground.

(c) The second ball will have larger acceleration.

(d) Both balls will have the same acceleration.

Answer

C

Physics Bowl (2017)A small object is released from rest and falls freely for 4.00 �푠 until reaching the ground.

What was the height above the ground from which the object was released?

(A) 10.0 �푚

(B) 20.0 �푚

(C) 40.0 �푚

(D) 80.0 �푚

(E) 160.0 �푚

Answer

D

Physics Bowl (2017)A mass moves along the x-axis following

the position vs. time graph provided.

During what time interval(s) does the

mass have an acceleration of 0 �푚/�푠2

? Time

is represented as �푡.

(A) only from 0 �푠 < �푡 < 3 �푠 (B) only at �푡 = 5 �푠 (C) only from 7 �푠 < �푡 < 10 �푠 (D) only from 0 �푠 < �푡 < 3 �푠 and 7 �푠 < �푡 < 10 �푠 (E) only from 0 �푠 < �푡 < 3 �푠, �푡 = 5 �푠, and 7 �푠 < �푡 <

10 s

Answer

D

Physics Bowl (2014)Starting from rest, a cart uniformly accelerates to a speed of 7.60 �푚/�푠 in a time of 3.00 �푠. Through what distance does the cart move in this time?

(A) 5.7 �푚

(B) 8.1 �푚

(C) 11.4 �푚

(D) 16.1 �푚

(E) 22.8 m

Answer

C

Fnet=ma (2007) An object is released from rest and falls a distance h during the first second of time.

How far will it fall during the next second of time?

(a) h

(b) 2h

(c) 3h

(d) 4h

(e) h

2

Answer

C

Fnet=ma (2009) A bird is flying in a straight line initially at 10 m/s. It uniformly increases its speed to

15 m/s while covering a distance of 25 m. What is the magnitude of the acceleration of

the bird?

(A) 5.0 m/s

2

(B) 2.5 m/s

2

(C) 2.0 m/s

2

(D) 0.5 m/s

2

(E) 0.2 m/s

2

Answer

B

Fnet=ma (2009) A person standing on the edge of a fire escape simultaneously launches two apples, one

straight up with a speed of 7 m/s and the other straight down at the same speed. How

far apart are the two apples 2 seconds after they were thrown, assuming that neither

has hit the ground?

(A) 14 m

(B) 20 m

(C) 28 m

(D) 34 m

(E) 56 m

Answer

C

Fnet=ma (2010) The following question refers to the graph which

shows a representation of the motion of a squirrel

as it runs in a straight-line along a telephone wire.

The letters A through E refer to the indicated

times.

If the graph is a graph of POSITION vs. TIME,

then the squirrel has the greatest speed at what

time(s) or during what time interval(s)?

(A) From A to B

(B) From B to C only

(C) From B to D

(D) From C to D only

(E) From D to E

Answer

C

Fnet=ma (2009) A person standing on the edge of a fire escape simultaneously launches two apples, one

straight up with a speed of 7 m/s and the other straight down at the same speed. How

far apart are the two apples 2 seconds after they were thrown, assuming that neither

has hit the ground?

(A) 14 m

(B) 20 m

(C) 28 m

(D) 34 m

(E) 56 m

Answer

C

Fnet=ma (2011)A cyclist travels at a constant speed of 22.0 km/hr except for a 20 minute stop. The

cyclist’s average speed was 17.5 km/hr. How far did the cyclist travel?

(A) 28.5 km

(B) 30.3 km

(C) 31.2 km

(D) 36.5 km

(E) 38.9 km

Answer

A