a 28 kg mass suspends from a light rope 18 m long & is held to one side by the horizontal force, f, as shown below.
the distance, s, 11.1 m. find f.

215.15 N

Explanation:

If we draw a free body diagram of the mass we will have the following:

(1)

(2)

Where is the tension force of the rope, the mass, the acceleration due gravity and is the weight.

On the other hand, we can calculate as follows:

Where and

(3)

Now, we firstly need to find from (2):

(4)

(5)

Substituting (5) in (1):

(6)

Finally:

note: the given question is incomplete.

complete question is given below.

which is an example of kinetic energy?

a. the energy stored in ethanol  

b. a hockey puck sliding across the ice  

c. a compressed spring  

d. a ball sitting at the top of a ramp

solution: the kinetic energy is the energy posses by the virtue of the motion of the object.

in the given options, a, c and d are the example of potential energy because it is the energy posses by the virtue of the rest of the object. but option b has the kinetic energy as the object is in motion.

hence, a hockey puck sliding across the ice   is the apex example of kinetic energy.

so, the option (b) a hockey puck sliding across the ice   is the correct option.