Question

QUESTION 1:

We can roughly model a gymnastic tumbler as a uniform solid cylinder of mass 75.0 kg and diameter 1.20 m .

A) If this tumbler rolls forward at 0.450 rev/s, how much total kinetic energy does he have? K=

B) What percent of his total kinetic energy is rotational? Krot/K=

QUESTION 2:

A 2.70-kg grinding wheel is in the form of a solid cylinder of radius 0.100 m.

A) What constant torque will bring it from rest to an angular speed of 1200 rev/min in 2.5 s?

B) Through what angle has it turned during that time?

C) Use equation W=τz(θ2−θ1)=τzΔθ to calculate the work done by the torque.

D) What is the grinding wheel’s kinetic energy when it is rotating at 1200 rev/min?

E) Compare your answer in part (D) to the result in part (C).

The results are the same.

The results are not the same.

Answer 1

The total kinetic energy is the sum of the rotational kinetic energy and translational kinetic energy. Use the equation for rotational kinetic energy and total kinetic energy to find the required percentage as shown below