A60.0-kg crate rests on a level floor at a shipping dock. the coefficients of static and kinetic friction are 0.760 and 0.410, respectively. what horizontal pushing force is required to (a) just start the crate moving and (b) slide the crate across the dock at constant speed? important: assume that the pushing force is to the right

(a) 446.88 N

(b) 241.08 N

Explanation:

m = 60 kg, μs = 0.760, μk = 0.410

(a) To just start the crate moving: the coefficient of friction is static.

F = μs m g

F = 0.760 x 60 x 9.8

F = 446.88 N

(b) To slide the crate with constant speed: the coefficient of friction is kinetic.

F = μk m g

F = 0.410 x 60 x 9.8

F = 241.08 N

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.