Question 1

A 6.00-kg block is in contact with a 4.00-kg block on a horizontal frictionless surface as shown. A horizontal force of 20.0 N is applied to the 6.00-kg block. What is the magnitude of the force that the 6.00-kg block exerts on the 4.00-kg block?

Accepted Answer

$$12.0\ \mathrm{N}$$

Question 2

Three objects are connected as shown in the figure. The strings and frictionless pulleys have negligible masses, and the coefficient of kinetic friction between the 2.0-kg block and the table is $$\mu_k = 0.25. $$What is the acceleration of the 2.0-kg block?

Accepted Answer

$$1.7\ \mathrm{m/s^2$}$$

Question 3

Two blocks are connected by a string that goes over an ideal pulley as shown. Block A has a mass of $$3.00\ \mathrm{kg}$$ and can slide along a rough plane inclined $$30.0^\circ to $$the horizontal. The coefficient of static friction between block A and the plane is $$0.400. $$What mass should block B have in order to start block A sliding up the plane?

Accepted Answer

$$2.8\ \mathrm{kg}$$

Question 4

Two objects are connected by a very light flexible string as shown, where $$M = 0.60\ \mathrm{kg}$$ and $$m = 0.40\ \mathrm{kg}. $$You can ignore friction and the mass of the pulley. What is the magnitude of the acceleration of each object?

Accepted Answer

$$1.96\ \mathrm{m/s^2$}$$

Question 5

The figure shows a $$100\ \mathrm{kg}$$ block being released from rest from a height of $$1.0\ \mathrm{m}. It $$takes $$0.90\ \mathrm{s} to $$reach the floor. What is the mass $$m of $$the other block? (Assume the pulley is massless and frictionless.)

Accepted Answer

$$54\ \mathrm{kg}$$

Question 6

According to Newton’s third law, if object A exerts a force $$\vec{F} on $$object B, what force does object B exert on object A?

Accepted Answer

$$-\vec{F}$$, equal in magnitude and opposite in direction

Question 7

A person is pushing a crate across a rough floor. Which force propels the person forward as they walk?

Accepted Answer

Static friction

Question 8

In a tug-of-war, two students pull on opposite ends of a massless rope with $$100\ \mathrm{N}$$ each. What is the tension in the rope?

Accepted Answer

$$100\ \mathrm{N}$$

Question 9

A mosquito runs head-on into a truck. Which is true during the collision?

Accepted Answer

The mosquito exerts the same force on the truck as the truck exerts on the mosquito.

Question 10

Two blocks, A and B, are connected by a massless string and pulled to the right on a frictionless surface. Block A has a larger mass than B. How do the two tension forces compare?

Accepted Answer

$$T_1$$ \u003e $$T_2$$

Question 11

A block of mass $$m is $$hanging from a massless, frictionless pulley and is connected to a block of mass $$M on $$the other side. If $$M \u003e m$$, what is the acceleration of the system?

Accepted Answer

$$a = \dfrac{(M - m)g}{M + m}$$

Question 12

A block of mass $$m is $$accelerated downward by gravity while attached to a massless string over a massless, frictionless pulley. What is the tension $$T in $$the string if the block accelerates downward with acceleration $$a$$?

Accepted Answer

$$T = m(g - a)$$

Question 13

Which of the following best describes an action/reaction pair according to Newton’s third law?

Accepted Answer

The gravitational force of the Earth on a ball and the gravitational force of the ball on the Earth.

Question 14

If two objects are connected by a massless string over a massless, frictionless pulley and move together, what is the acceleration constraint between their accelerations $$a_A$$ and $$a_B$$?

Accepted Answer

$$a_A = -a_B$$

Question 15

A car is propelled forward on a road. What is the origin of the propulsion force?

Accepted Answer

Static friction between the tires and the road

Question 16

A block is being pulled by a rope over a frictionless surface. If the rope is massless and the block is accelerating, what can be said about the tension throughout the rope?

Accepted Answer

The tension is the same throughout the rope.

Newton’s Third Law and Interacting Objects: Step-by-Step Guidance

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