A block is in contact with a surface. How does the coefficient of kinetic friction vary with the mass of the block?

"A solid $200\text{-g}$ block of lead and a solid $200\text{-g}$ block of copper are completely submerged in an aquarium filled with water. Each block is suspended just above the bottom of the aquarium by a thread. Which of the following is true? $(a)$ The buoyant force on the lead block is greater than the buoyant force on the copper block. $(b)$ The buoyant force on the copper block is greater than the buoyant force on the lead block. $(c)$ The buoyant force is the same on both blocks. $(d)$ More information is needed to choose the correct answer."

Describe and correct the error in the conditional statement about lines. If there is a line and a point not on the line, then there is exactly one line through the point that intersects the given line.

A block is resting on a rough inclined surface. You deserve that by increasing the angle of the incline, you can make the block start moving down the incline. Which answer best explains why the block starts moving? (a) By increasing the angle of the incline, you increase the component of the force exerted by Earth on the block, which pulls the block down the incline. (b) By increasing the angle of the incline, you decrease the maximum static friction force exerted on the block by the surface. (c) By increasing the angle of the incline, you simultaneously increase the component of the force exerted by Earth on the block and decrease the maximum static friction force exerted on the block.

Line j is perpendicular to the line with the given equation and line j passes through point P. Write an equation of line j. y=-3 x-4 ; P(1,1)

If the contact surface between the $20-\mathrm{kg}$ block and the ground is smooth, determine the power of force $F$ when $t=4$ s. Initially, the block is at rest.

A block is dropped onto a spring with $k=30 \mathrm{~N} / \mathrm{m}$. The block has a speed of $3.3 \mathrm{~m} / \mathrm{s}$ just before it strikes the spring. If the spring compresses an amount $0.12 \mathrm{~m}$ before bringing the block to rest, what is the mass of the block?

Consider a hole in a block of steel such as the cylinder in a steel engine block. Will the diameter of this hole get larger or smaller when the steel is heated? By how much will it change?

Consider the following recursive function:

void funcRec(int u, char v)                            //Line 1
{
    if (u == 0)                                        //Line 2
        cout << v;                                    //Line 3
    else                                               //Line 4
    {                                                   //Line 5
        char w;                                        //Line 6
        w = static_cast < char >
            (static_cast < int > (v) + 1);             //Line 7
        funcRec(u - 1, w);                             //Line 8
    }                                                  //Line 9
}
Answer the following questions:

a. Identify the base case. b. Identify the general case. c. What is the output of the following statement? funcRec(5, 'A');

Consider the two-block system shown in given Example. Is the non conservative work done on block 2 by the tension in the rope positive, negative, or zero? Explain.

a block of stagnant air with the given dimensions;

The homogeneous wooden block $A$ of the given figure is $0.7 \mathrm{~m}$ by $0.7 \mathrm{~m}$ by $1.3 \mathrm{~m}$ and weighs $2.4\ \mathrm{kN}$. The concrete block $B$ (specific weight $=23.6 \mathrm{kN} / \mathrm{m}^3$ ) is suspended from $A$ by means of the slender cable causing $A$ to float in the position indicated. Determine the volume of $B$.

A 6000-kg dump truck has a 1500-kg stone block sitting in its bed when the operator accidently raises the bed to an angle of $30^o$. At this angle, the cables holding the block in place break, so the block slides down the bed and impacts the tailgate. Neglecting friction between the block and the bed and assuming the truck can roll freely, deter-mine the speed of the truck and the block (a) immediately before the block hits the tailgate, (b) immediately after the block hits the tail-gate. Assume a plastic impact.

Discuss qualitatively the motion of the atoms in a block of steel that falls onto another steel block. Why and how do large-scale vibrations damp out?