Physics Motion Quiz 09

Describe the motion of the object at t = 3 seconds.

• speeding up

• slowing down

• constant speed

• at rest

• turning around

Answer explanation

At t = 3 seconds, the object is at rest, meaning it is not moving. This indicates that its speed is zero, confirming that it is not speeding up, slowing down, or moving at a constant speed.

Tags

NGSS.MS-PS3-1

Describe the motion of the object at t = 3 seconds.

• speeding up

• slowing down

• constant speed

• at rest

• turning around

Answer explanation

At t = 3 seconds, the object is moving at a constant speed, indicating that its velocity is steady and not changing. This rules out options like speeding up or slowing down.

Tags

NGSS.MS-PS3-1

You enter the freeway at mile marker 10 and drive north at 50 mph for 1.5 hours until you reach your exit. What is your exit (mile marker) number? (Write the number without units.)

Answer explanation

You start at mile marker 10 and drive for 1.5 hours at 50 mph. Distance = speed × time = 50 mph × 1.5 hours = 75 miles. Adding this to the starting point: 10 + 75 = 85. Therefore, your exit is at mile marker 85.

An ant is moving in the negative direction along a meter stick with an average speed of 2.5 cm/s. If you start your timer when the ant is at 65 cm, what is the ant’s position when your timer reads 12 s? (Write the number without units.)

Answer explanation

The ant moves at 2.5 cm/s for 12 s, covering 30 cm. Starting at 65 cm, its position is 65 cm - 30 cm = 35 cm. However, the ant cannot go beyond 0 cm, so the correct position is 0.

The diagrams plot "trips" taken by four insects by showing the locations of each insect at different times. The dots show where an insect is at a given time and the number next to the dots indicates the time (in seconds) when the insect is at that point. At t= 0, all four insects are moving in straight lines from left to right. Which insect had the highest average speed for the 5-second trip?

• Bug A because it went the greatest distance in the 5 seconds.

• Bug B because it went the greatest distance in the 5 seconds.

• Bug C because it traveled faster at the beginning.

• Bug D because it traveled the greatest distance in any time interval.

Answer explanation

Bug B had the highest average speed because it covered the greatest distance in the 5 seconds, as indicated by the positions plotted at each time interval.

Tags

NGSS.MS-PS3-1

The graph represents the relationship between velocity and time for an automobile moving in a straight line. Using any 1-s interval, find the automobile’s acceleration.

• 0 m/s/s

• 1 m/s/s

• 5 m/s/s

• 10 m/s/s

Answer explanation

To find acceleration, use the formula: acceleration = (final velocity - initial velocity) / time. If the velocity changes from 0 m/s to 5 m/s in 1 second, acceleration = (5 m/s - 0 m/s) / 1 s = 5 m/s².

The graph below shows the velocity of an automobile vs. time as the automobile accelerates on a road. An automobile that has a greater acceleration would have a velocity vs. time graph that has a:

• steeper slope.

• slope that is less steep.

• higher velocity at t = 0.

• lower velocity at t = 0.

Answer explanation

A greater acceleration results in a steeper slope on a velocity vs. time graph, indicating that the velocity increases more rapidly over time. Therefore, the correct choice is a steeper slope.

Tags

NGSS.HS-PS2-1

The velocity vs. time graph for two automobiles is shown. At time t, the automobiles have the same:

• velocity, acceleration, and distance traveled.

• velocity and acceleration.

• velocity only.

• acceleration only.

Answer explanation

At time t, the velocities of the automobiles may differ, but their acceleration is the same as indicated by parallel slopes on the graph. Therefore, they have the same acceleration only.

Tags

NGSS.MS-PS3-1

Look at the speed vs. time graph for Object 1 and Object 2. Which object had the greatest acceleration and why?

• Object 1; it has the greatest change in speed.

• Object 2; it has the fastest final speed.

• Object 1; it has greater constant speed.

• Object 2; it has the highest average speed.

Answer explanation

Object 1 had the greatest change in speed, indicating the highest acceleration. Acceleration is defined as the change in speed over time, so a larger change in speed directly correlates to greater acceleration.

Tags

NGSS.MS-PS3-1

The graph represents the motion of an object. Which of the following statements is true of the object’s acceleration?

• The object travels with constant speed so it doesn’t accelerate.

• The object has constant acceleration from 0 to 2 seconds.

• The object accelerates at 2 seconds.

• The object has increasing acceleration from 0 to 2 seconds and constant acceleration from 2 to 4 seconds.

• The object is at rest so it doesn’t accelerate.

Answer explanation

The object accelerates at 2 seconds, indicating a change in velocity. The other options incorrectly describe the object's motion or state.

Tags

NGSS.MS-PS3-1