a concrete brick is placed on a polished wood board which is initially laying horizontally on the floor. the static coefficient of friction is 0.63 between the board and the brick. the kinetic coefficient of friction is 0.55 between the two surfaces. we gradually raise one end of the wood board so that the board is tilted to increasingly larger angles, θ, relative to the horizontal. calculate the critical angle, θcrit at which the brick will start to slide along the wood board.

explanation:

the masses of the objects and the distance between them

i think its c if i'm wrong

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.