Fundamentals 1

Question 1

a rope connects two objects of different masses, where m1 > m2. The cart of mass m1 is on a frictionless surface. The cart of mass m2 is hanging off the table. The mass of the pulley is negligible.

Is the tension in the rope greater, less than, or equal to m2g?

Answer 1

less than. (If released from rest, block 2 speeds up downward, so acceleration is down, so forces are unbalanced down making the up force - tension - less than the downward weight.)

Question 2

a rope connects two objects of different masses, where m1 > m2. The cart of mass m1 is on a frictionless surface. The cart of mass m2 is hanging off the table. The mass of the pulley is negligible.

Is the acceleration of m1 greater than, less than, or equal to g?

Answer 2

less than. (Block isn’t in free fall - there’s an up force as well as weight.)

Question 3

a rope connects two objects of different masses, where m1 > m2. The cart of mass m1 is on a frictionless surface. The cart of mass m2 is hanging off the table. The mass of the pulley is negligible.

Which object experiences a larger force of the rope on the object?

Answer 3

neither, same rope force. (Jacobs law of tensions: one rope equals one tension. (The physics C corollary to Jacobs Law says “…unless interrupted by a massive object.) )

Question 4

a rope connects two objects of different masses, where m1 > m2. The cart of mass m1 is on a frictionless surface. The cart of mass m2 is hanging off the table. The mass of the pulley is negligible.

Which object has a larger magnitude of acceleration?

Answer 4

neither, same acceleration. (Acceleration is the change in speed every second. Since the objects are attached to one another, when one speeds up or slows down, the other one does too.)

Question 5

a rope connects two objects of different masses, where m1 > m2. The cart of mass m1 is on a frictionless surface. The cart of mass m2 is hanging off the table. The mass of the pulley is negligible.

What is the direction of the acceleration of m2?

Answer 5

down. (If released from rest, m2 will speed up downward; if given an initial upward speed, m2 will move up and slow down. In either case, acceleration is downward.)

Question 6

a rope connects two objects of different masses, where m1 > m2. The cart of mass m1 is on a frictionless surface. The cart of mass m2 is hanging off the table. The mass of the pulley is negligible.

What is the direction of the velocity of m1?

Answer 6

unknown. (The unbalanced force on m1 is right, but that could EITHER mean speeding up and moving right OR slowing down and moving left.)

Question 7

Write two expressions for impulse.

Answer 7

Impulse = change in momentum; Impulse = Ft.

Question 8

What is determined by the area under a force vs. displacement graph?

Answer 8

work.

Question 9

When an object undergoes simple harmonic motion, what is the direction of the force that the object experiences?

Answer 9

toward the equilibrium position.

Question 10

On a position-time graph, how is the location of an object determined?

Answer 10

from the vertical axis value.