Unit 3 Semester Review

Unit 3: Newton's 1st Law

Multiple Choice

A block is being pulled across a table with a rope. The following graph shows the block's velocity as a function of time. At what time interval are the forces acting on the block balanced?

• From t = 0-4 seconds

• From t = 4-6 seconds

• At t = 4 seconds

• At no point in the 6 seconds of the graph

Multiple Choice

A block is being pulled across a table with a rope. The following graph shows the block's velocity as a function of time. At what time interval is the block experiencing the greatest net force?

• From t = 0-4 seconds

• From t = 4-6 seconds

• At t = 4 seconds

• At no point in the 6 seconds of the graph

Multiple Choice

An object is pulled by a horizontal tension force along flat ground. The object is speeding up with a constant acceleration. The object experiences a force of friction. Which of the following could be true about the force on this object?

• The force of friction between the ground and the object is less than the tension force.

• The force of friction between the ground and the object is equal to the tension force.

• The force of friction between the ground and the object is greater than the tension force.

• The force of friction and the tension force act in the same direction.

Multiple Choice

The graph shows the position of an object as a function of time. Which statement is true about the net force acting on this object?

• The net force is increasing.

• The net force is decreasing.

• The net force is zero.

• The net force is a constant non-zero number.

Multiple Choice

A car with a mass of m and a truck with a mass of 3m both experience the same net force of F. Which of the following statements is true about this acceleration of each vehicle?

• The car and truck are experience the same acceleration, because they experience the same net force.

• The car's acceleration is less than the truck's acceleration, because the car has a smaller mass.

• The car's acceleration is greater than the truck's acceleration, because the truck has a larger mass.

• The acceleration cannot be determined based on the information given.

Multiple Choice

A ball is moved from Earth to a planet that has a gravitational acceleration that is double that of Earth. How does the gravitational force on the ball when it is on the new planet compare to the gravitational force on the ball when it is on Earth?

• The gravitational force on the ball when it is on the new planet is double the force on the ball when it is on Earth.

• The gravitational force on the ball when it is on the new planet is half the force on the ball when it is on Earth.

• The gravitational force on the ball when it is on the new planet is the same as the force on the ball when it is on Earth.

• The gravitational force on the ball when it is on the new planet is one-fourth the force on the ball when it is on Earth.

Multiple Choice

Which graph matches the following free body diagram?

Multiple Choice

A block with mass M is pulled to the right with force F, resulting in an acceleration A. Friction between the block and the surface is negligible. If a block of mass 2M is pulled with a force 2F, what is the acceleration of the new block?

• 1/2a

• a

• 2a

• 4a

Multiple Choice

Given the net forces on and the masses of the blocks shown above, which of the following correctly lists the blocks in order of Greatest to Least Acceleration?

• Block A > Block B > Block C = Block D

• Block C > Block D > Block B > Block A

• Block C > Block B > Block D = Block A

• Block C > Block D = Block A > Block B

Multiple Choice

In the figure below, on which side of the pulley will the string accelerate downward?

• right side

• left side

• will not accelerate

Multiple Choice

In the modified Atwood machine above block X sits on a frictionless table and the system has an acceleration of A. If the two blocks were switched places how would the new acceleration compare to A?

• No change to A, because the total mass of the system remains the same

• No change to A, because the difference between masses remains the same

• Decrease to ½ A, because the net force accelerating the system has decreased by ½

• Decrease to 1/3 A, because block X is 1/3 of the total system mass

Explanation Slide...

The heavier side will accelerate downward.

Multiple Choice

A 5 kg block is set on a rough table and connected to a hanging mass by a long string that passes over an ideal pulley. The system is released from rest at time t = 0, and the block speeds up as the mass falls. Once the mass m strikes the floor, at t = 4 sec, the block slows until it comes to rest again. A student uses measurement apparatus to collect data of the block’s velocity as a function of time. The data are shown in the graph below.

During what time period does the 5 kg block experience balanced horizontal forces?

• From t = 0 – 4 sec

• From t = 4 -6 sec

• At t = 4 sec

• At no point in the 6 seconds shown in the graph

Multiple Choice

1. Which of the following sets of masses will produce the greatest acceleration on an Atwood machine?

• Mass A 0.5 kg, Mass B 2.5 kg

• Mass A 1.5 kg, Mass B 3.5 kg

• Mass A 2.5 kg, Mass B 4.5 kg

• Mass A 3.5 kg, Mass B 5.5 kg

Multiple Choice

A 5 kg block is set on a rough table and connected to a hanging mass by a long string that passes over an ideal pulley. The system is released from rest at time t = 0, and the block speeds up as the mass falls. Once the mass m strikes the floor, at t = 4 sec, the block slows until it comes to rest again. A student uses measurement apparatus to collect data of the block’s velocity as a function of time. The data are shown in the graph below.

At what time does the net horizontal force on the 5 kg block have the largest magnitude?

• From t = 0 – 4 sec

• From t = 4 -6 sec

• At t = 4 sec

• The net horizontal force remains the same for the 6 seconds shown in the graph

Multiple Choice

For the system of attached masses m1 & m2, which mass will have a higher acceleration?

• m1

• m2

• Both will have same acceleration because they're attached by a string

Explanation Slide...

You want the biggest mass difference with the smallest total mass.

Multiple Choice

1. An astronaut brings an Atwood Machine to the Moon, where the force of gravity is only one sixth of its strength on Earth. She places a 2.0 kg mass on one end of the rope, and a 3.0 kg mass on the other end of the rope. What will the astronaut observe when she releases the masses?

• The masses will accelerate faster than they would on Earth.

• The masses will accelerate more slowly than they would on Earth.

• • The measured acceleration will be exactly the same as on Earth.

• There will be zero acceleration of the masses on the Moon.

Explanation Slide...

There is less gravitational force on the Moon.

Multiple Choice

A group of students are told to measure the acceleration of the Atwood machine pictured above. One student suggests that they use a 2 kg and 4 kg mass instead. How will the acceleration of the system with 2 kg and 4 kg masses compare to the original system?

• The acceleration of the new system will be smaller because the mass difference of the system is smaller

• The acceleration of the new system will be larger because the mass difference of the system is smaller

• The acceleration of the new system will be no change because the total mass of the system is the same

• The acceleration of the new system will be no change because the mass difference has no effect

Explanation Slide...

They have the same total mass as the original masses, but the mass difference is less so the acceleration will be smaller.

Multiple Choice

A group of students are told to measure the acceleration of the Atwood machine pictured above. One student suggests that they use a 4 kg and 2 kg mass instead. How will the acceleration of the system with 4 kg and 2 kg masses compare to the original system?

• The acceleration of the new system will be larger because the total mass of the system is larger

• The acceleration of the new system will be larger because the 4 kg mass has more weight

• The acceleration of the new system will be smaller because the total mass of the system is larger

• The acceleration of the new system will be smaller because the 2 kg mass has more weight

Explanation Slide...

The total mass increased so the acceleration decreased.