Jogger A has a mass m and a speed v, jogger B has a mass * and a speed 3v, jogger C has a mass 3m and a speed , and jogger D has a т Part A mass 4m and a speed Rank the joggers in order of decreasing kinetic energy. Indicate ties where appropriate. Rank from highest to smallest. To rank items as equivalent, overlap them. Reset Help |highest energy smallest energy - TL- ------ e-l - -----L- da- -- Rearson

To find the difference in gravitational potential energies, the difference in heights is used. What is used to find the difference in kinetic energies?

A particle of mass 2.0 kg moves under the influence of the force F(x)=(3/x)N. If its speed at x=2.0 m is v=6.0 m/s, what is its speed at x = 7.0 m?

Does the kinetic energy of an object depend on the frame of reference in which its motion is measured? Provide an example to prove this point.

Is Earth an inertial frame of reference? Is the sun? Justify your response.

How fast would a 6.0 m-long sports car have to be going past you in order for it to appear only 5.5 m long?

A person drops a pebble of mass m1from a height h, and it hits the floor with kinetic energy K. The person drops another pebble of mass m2, from a height of 2h , and it hits the floor with the same kinetic energy K. How do the masses of the pebbles compare?

(a) Find the value of for the following situation. An astronaut measures the length of his spaceship to be 100 m, while an observer measures it to be 25.0 m. (b) What is the of the spaceship relative to Earth?

A particle of m has a velocity of . Is its kinetic energy given by ? If not, what is the correct expression?

A bungee cord is essentially a very long rubber band that can stretch up to four times its unstretched length. However, its spring constant vanes over its stretch [see Menz, P.G. “The Physics of Bungee Jumping.” The Physics Teacher (November 1993) 31: 483-487]. Take the length of the cord to be along the direction and define the stretch as the length of the cord minus its un-stretched length that is, (see below). Suppose a particular bungee cord has a spring constant, for of and for. (Recall that the of (Recall that the spring constant is the slope of the force versus its stretch (a) What is the tension in the cord when the stretch is 16.7 m (the maximum desired for a given jump)? (b) How much work must be done against the elastic force of the bungee cord to stretch It 16.7 m? Figure 7.16 (credit modification of work by Graeme Churchard)