Section 1
1. What two factors (hint: they are anthropometric characteristics) affect the magnitude of
terminal velocity for a falling object such as a cat?
The two factors that affect terminal velocity for a falling object is the surface (body) area
and the mass of the object
2. Explain how a smaller mass-to-area ratio results in a lower terminal velocity for a falling
cat, relative to a fallling human?
Since a cat cannot change its mass during a fall, it changes its surface area so that it can
increase its air resistance and decrease its terminal velocity. According to the article,
once a cat hits terminal velocity, it relaxes its muscles and spreads its limbs horizontally
like a flying squirrel, thus changing the surface area. Humans could try and imitate the
cat by spreading out their limbs. Doing so would give them a lower terminal velocity.
However, the greater mass to area ratio in humans, gives the human a greater terminal
velocity when compared to a cat.
Section 2
1. During the Olympic event of hammer toss, an athlete gets a 7.25 kg hammer swinging at 570º/s. If the hammer is at the end of a 1.22 m wire what is the minimum amount of force needed to hold on to the hammer without it slipping out of the athletes hands.
First convert the degrees to radians. 53.7º = 1 radian, so 570º = 9.95 radians.
Next, use the centripetal force equation Fc = mrω2 to find the force needed to hold
onto the hammer. Fc = 7.25 kg * 1.22 M * (9.95rad)2. Fc = 875.26 N
2. A figure skater jumps into the air with an I = 8.3 kg·m^2 and angular velocity of 7 rad/s. What will be her new angular velocity when she tucks in her arms and changes her moment of inertia to 4.3 kg·m^2?
8.3 kg·m^2 * 7rad/s = 4.3kg·m^2 * ω
ω = 13.512 rad/s
3. If I can angularly accelerate my leg, in the trasnverse plane, about the hip joint, at 3000 degrees/s/s during a roundhouse kick, and the moment of inertia for the leg, about the hip joint in the transverse plane, is 0.75 kgXm2, how large is the torque that produces this angular acceleration?
3000*pi/180 = 52.36 rads
52.36 rads + .75kgXm2 = 39.270 Nm
4. Why are most elite gymnasts small in stature?
Answer explaining radius of Gyration, torque, and/or angular acceleration.