EFHS -- acceleration

Which statement explains why the cyclist in the diagram is accelerating?

• The speed of the cyclist is changing.

• The velocity is changing per unit of time.

• The direction and speed of the cyclist is changing.

• The direction of the cyclist is not changing.

In the graph, which line segment shows an object moving at a constant velocity.

• B

• C

• D

• A

A car speeds up from 0 to 30 m/s in 15s.  What is the acceleration?

• 450 m/s²

• 2 m/s

• 2 m/s²

• 450 m/s

What are the units for acceleration?

• velocity and time

• m/s

• mph

• m/s²

In which time segment is the cyclist accelerating, and why?

• segment A-B, because the cyclist is changing speed per unit of time.

• segment A-B, because the cyclist is not changing direction.

• segment B-C, because the cyclist is maintaining constant velocity.

• segment C-D, because the cyclist has reached the fastest velocity.

A boy drops a rock from the top of a cliff.  If the rock started at v = 0, how fast is it going after 7s?  (acceleration due to gravity is -9.81m/s²)

• 1.4 m/s

• -68.67 m/s

• 27.33 m/s

• -27.33 m/s

Under which conditions can an object have negative acceleration but increasing speed?

• acceleration and velocity have opposite signs

• acceleration and displacement have opposite signs

• velocity and displacement have the same sign

• acceleration and velocity have the same sign

A child on a playground slides down a slide with an acceleration of 4.8 m/s² .  If he started at rest, and takes 5s to reach the bottom of the slide, how long is the slide?

• 60 m

• 14 m

• -48 m

• 22 m

The astronaut dropping the hammer and feather on the surface of the moon demonstrates what concept about falling objects?

• All objects in free fall have the same displacement.

• All objects in free fall have the same rate of acceleration.

• Only objects on the moon’s surface have the same acceleration due to gravity.

• All falling objects have the same velocity.