Approximately how far will an object near Earth's surface fall in 3.0 seconds?

• 88 m

• 9.8 m

• 44 m

• 29 m

Answer explanation

Use d = v_it + 1/2 at²

Tags

NGSS.HS-PS2-1

A rock falls from rest off a high cliff. How far has the rock fallen when its speed is 39.2 meters per second? [Neglect friction.]

• 123 m

• 44.1 m

• 78.3 m

• 19.6 m

Answer explanation

Use v_f² = v_i² + 2ad

Tags

NGSS.HS-PS2-1

NGSS.HS-PS2-4

A ball dropped from rest falls freely until it hits the ground with a speed of 20 meters per second. What is the approximate time during which the ball is in free fall?

• 2 s

• 10 s

• 1 s

• 0.5 s

Answer explanation

Use v_f = v_i + at

Tags

NGSS.MS-PS2-2

A ball thrown vertically upward reaches a maximum height of 30. meters above the surface of Earth. At its maximum height, the speed of the ball is

• 0.0 m/s

• 24 m/s

• 9.8 m/s

• 3.1 m/s

Answer explanation

Speed is 0 at max height

An object falls freely from rest near the surface of Earth. What is the speed of the object after having fallen a distance at 4.90 meters?

• 9.80 m/s

• 96.1 m/s

• 4.90 m/s

• 24.0 m/s

Answer explanation

Use v_f² = v_i² +2ad

Tags

NGSS.HS-PS2-1

An object is dropped from rest and falls freely 20. meters to Earth. When is the speed of the object 9.8 meters per second?

• during the entire first second of its fall

• at the end of its first second of fall

• after it has fallen 9.8meters

• during the entire time of fall

Answer explanation

it accelerates due to gravity at 9.81 m/s², which means that it is increasing its speed by 9.81 m/s, every second. So starting from 0, at the end of one full second it will have reached a speed of 9.8m/s

Tags

NGSS.HS-PS2-4

Which of the following graphs best represents the relationship between the acceleration of an object falling freely near the surface of Earth and the time that it falls?

• 
• 
• 
• 

Answer explanation

Acceleration is a constant value of 9.81 m/s²

Tags

NGSS.HS-PS2-1

An astronaut standing on a platform on the Moon drops a hammer. If the hammer falls 6.0 meters vertically in 2.7 seconds, what is its acceleration?

• 9.8 m/s²

• 4.4 m/s²

• 1.6 m/s²

• 2.2 m/s²

Answer explanation

Use d = v_it + 1/2 at². Do NOT get fooled - you aren't on Earth (so its not 9.81!) you are on the Moon!

Tags

NGSS.HS-PS2-1

Which is constant for a freely falling object?

• displacment

• acceleration

• velocity

• speed

Answer explanation

Only acceleration is constant in free fall on Earth, at 9.81m/s²

Tags

NGSS.HS-PS2-4

As shown in the diagram, an astronaut on the Moon is holding a baseball and a balloon. The astronaut releases both objects at the same time. What does the astronaut observe? [NOTE: The Moon has no atmosphere.]

• The baseball and balloon remain suspended and do not fall

• The baseball falls slower than the balloon

• The baseball falls faster than the balloon

• The baseball and balloon fall at the same rate

Answer explanation

With no air resistance, all objects fall at the same rate

Tags

NGSS.HS-PS2-4