Physics 1: Free Body Diagrams

As shown in the figure, two blocks with masses m and M (M>m) are pushed by a force F in both Case I and Case II. The surface is horizontal and frictionless. Let R1 be the force that m exerts on M in Case I and RII be the force that m exerts on M in Case II. Which of the following statements is true?

An Object with mass m and initial velocity v is brought to rest by a constant force F acting for a time t and through a distance d. Possible expressions for the magnitude of the force F are: i. $\frac{mv^2}{2d}$ ii. $\frac{2md}{t^2}$ iii. $\frac{mv}{t}$

ii only

iii only

i and ii only

ii and iii only

i, ii, and iii

A toy car of mass 6 kg moving in a straight path, experiences a net force given by the function F = -3t. At time t=0, the car has a velocity of 4 m/s in the positive direction and is located +8 m from the origin. The car will come instantaneously to rest at time t equal to

2/3 s

sqrt( 4/3 ) s

sqrt( 8/3 ) s

sqrt( 8) s

4 s

A block of mass M1 on a horizontal table is connected to a hanging block of mass M2 by a string that passes over a pulley, as shown in the figure below. The acceleration of the blocks is 0.6g. Assume that friction and the mass of the string are negligible. The tension T in the string is

In the situation above, what is the ratio of the masses?

0.67

1.0

1.4

1.5

1.6

Hercules and Carlos horizontally push in the same direction on a 1200 kg crate. Hercules pushes with a force of 500 N and Carlos pushes with a force of 300 N. If a frictional force provides 200 N of resistance, what is the acceleration of the crate?

1.3 m/s2

1.0 m/s2

0.87 m/s2

0.75 m/s2

0.5 m/s2

Determine the acceleration and the value of the normal force. Draw a free body diagram.

M = 10kg, $\theta$ = 30 degrees

Determine the acceleration of the system if M = 10 kg and m = 30 kg and $\theta$ = 30 degrees. Determine the tension in the rope as well.

The large block M is 20 kg, and the smaller block, m, is 1 kg. The coefficient of kinetic friction is 0.2. Determine the acceleration of the system and the tension in the cords. The angle of the inclined plane is 60 degrees to the horizontal. Also draw a free body diagram for both blocks.

Determine the acceleration of the system if m$_1$ = 5 kg and m$_2$ = 10 kg and m$_3$. Determine the tensions T, T$_1$ , and T$_2$ .

A 3 kg box is pushed on a surface with a force of F = 15 N. The coefficient of static friction, $\mu_s$ is 0.3, and the coefficient of kinetic friction, $\mu_k$ is 0.1.

A. Does the box move?

B. If it does move, calculate the acceleration of the box.

A M$_1$ = 8 kg box rests on a table and is connected to a second box of mass M$_2$ = 4 kg via a rope that hangs over a pulley as shown. The coefficient of static friction, $\mu_s$ is 0.2, and the coefficient of kinetic friction $\mu_k$ is 0.1. Use a free body diagrams to answer the following.

B. If the box does cause the system to move, what is the acceleration of the system, and the tension in the rope?

The large block m$_1$ is 10 kg, and the smaller block m$_2$ is 1 kg. The coefficient of kinetic friction is 0.1. Determine the acceleration of the system and the contact force between the blocks. The applied force, F is 30 N. Also draw a free body diagram for both blocks.

The large block m$_1$ is 6 kg, and the smaller block m$_2$ is 12 kg. The coefficient of kinetic friction is 0.2. Determine the acceleration of the system and the Tension T$_2$ . The applied force, F is 36 N. Also draw a free body diagram for both blocks.

A ball of mass M is thrown vertically upward with an initial speed of v0. It experiences a force of air resistance given by F=−kv, where k is a positive constant. The positive direction for all vector quantities is upward. Express all algebraic answers in terms of M, k, v0, and fundamental constants.

Does the magnitude of the acceleration of the ball increase, decrease, or remain the same as the ball moves upward?

Write, but do NOT solve, a differential equation for the instantaneous speed vof the ball in terms of time tas the ball moves upward.

Determine the terminal speed of the ball as it moves downward.

Does it take longer for the ball to rise to its maximum height or to fall from its maximal height back to the height from which it was thrown? Justify your answer.

Sketch a graph of velocity versus time for the upward and downward parts of the ball’s flight, where $t_f$ is the time at which the ball returns to the height from which it was thrown.

A small block of mass MB= 0.50 kg is placed on a long slab of mass MS= 3.0 kg as shown below. Initially, the slab is at rest and the block has a speed v0of 4.0 m/s to the right. The coefficient of kinetic friction between the block and slab is 0.20, and there is no friction between the slab and the horizontal surface on which it moves.

A block of mass mis pulled along a rough horizontal surface by a constant applied force of magnitude F1that acts at an angle θto the horizontal, as indicated below. The acceleration of the block is a1. Express all algebraic answers in terms of m, F1, θ, a1, and fundamental constants.

A rubber ball of mass m is dropped from a cliff. As the ball falls, it is subject to air drag (a resistive force caused by the air). The drag force on the ball has a magnitude bv2, where bis a constant drag coefficient and v is the instantaneous speed of the ball. The drag coefficient bis directly proportional to the cross-sectional area of the ball and the density of the air and does not depend on the mass of the ball. As the ball falls, its speed approaches a constant value called the terminal speed.

Draw and label all the forces on the ball at some instant before it reaches terminal speed.

State whether the magnitude of the acceleration of the ball of mass m increases, decreases, or remains the same as the ball approaches terminal speed. Explain.

Write, but do NOT solve, a differential equation for the instantaneous speed vof the ball in terms of time t, the given quantities, and fundamental constants.

Determine the terminal speed vtin terms of the given quantities and fundamental constants.

Determine the energy dissipated by the drag force during the fall if the ball is released at height hand reaches its terminal speed before hitting the ground, in terms of the given quantities and fundamental constants. (this question requires knowledge of potential and kinetic energy, often not introduced until later in a physics course)

What is the tension T in the rope if the 10-N weight is moving upward with a constant velocity?