Calculate the force exerted by the biceps to hold up the forearm and a book whose mass m= [m] kg. The pivot point is at the elbow joint. Solution: holding up → rotational equilibrium; Which influences tend to change the state of rotational motion ? Mass of forearm=2.5 kg.τ= F⋅lever arm;  τcounterclockwise= τclockwise τbiceps=τbook+τforearm Fbiceps⋅4cm= Weightbook⋅ 40cm +Weightarm ⋅ 15cm

If a net force applied to an object doubles, then itsA) velocity doubles.B) acceleration doubles.C) acceleration is cut in half.D) acceleration increases by a factor of four.

Our nails grow at a rate of 0.14mm per day at age 23. What is the average speed of fingernails in mmh ?A) 0.006mmh.B) 0.008mmh.C) 2.7mmh.D) 88.9mmh.

In order to prevent muscle contraction from mis-aligning bones during healing, broken legs must be supported horizontally and kept under tension (traction) directed along the leg. If the leg weighs [w] N, what must be the weight of the hanging mass ? The supporting wires make an angle of 30 degrees with respect to the floor.     

The slope of the graph below has a value close to    A) 1.8 ms2;  B) 2.4 ms2; C) 0.5 ms2; D) 4.7 ms2;

With all other factors equal, if you double the unbalanced force on an object of a given mass the acceleration will beA) doubled.B) increased fourfold.C) increased by one-half.D) increased by one-forth.

How many meters away is a cliff if an echo is heard one-half second after the original sound ? Assume that sound travels at 343.0ms. HINT: v=dt Solve for distance; What do we mean by the echo being heard one-half second after the original sound ? A) 86. meters; B)  860. meters; C)  8.6 meters; D) 8600 meters;

An objects ____ determines the extent of resistance to a change of motion.A) weightB) densityC) massD) Any of these.

In order to prevent muscle contraction from mis-aligning bones during healing, broken legs must be supported horizontally and kept under tension (traction) directed along the leg. If the leg weighs [w] N, what traction force does this hanging weight produce upon the leg ? The supporting wires make an angle of 30 degrees with respect to the floor. Hint 1: Tension in the wires is equal to the hanging weight. Hint 2 : Which component of the weight/tension contributes to the traction of the leg ? Hint 3: Forcealong the leg=2⋅Weight⋅cosθ

What feature of motion is described by acceleration?A) The rate at which speed changes.B) How quickly final velocity is reached.