Ahunter wishes to cross a river that is 1.5 km wide and flows with a velocity of 5.0 km/h parallel to its banks. the hunter uses a small powerboat that moves at a maximum speed of 12 km/h with respect to the water. what is the minimum time for crossing?

137.48 s

Explanation:

Given

Width of river=1.5 km

velocity of river=5 km/h

velocity of boat w.r.t river =12 km/h

To cross the river in minimum time hunter needs to cross the river perpendicular to the flow

i.e. velocity of boat w.r.t  water must be perpendicular

i.e. x component of boat must be equal to river flow

where is angle made by boat w.r.t bank

its vertical component is

Time taken

i think they are all correct

explanation:

they seem good

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.