A480-kilogram horse runs across a field at a rate of 40 km/hr. what is the magnitude of the horse's momentum?
a) 12 km/hr

b) 19,200 km/hr

c) 19,200 kg x km/hr

d) 12 kg x km/hr

We can assume the tongue begins to reach. we need to solve this using one of the kinematic equations of motion, solving in two parts. we assume the tongue begins at rest. firstly, the accelerating part. we have the following informtion: u = initial velocity = 0 m/s a = acceleration = 270 m/s² t = time = 0.020 s d = distance = ? d = ut + 1/2 at². since u = 0, this reduces to d = 1/2 at² = 135 * 0.020² = 0.054 m. now what about the constant speed part? first let's find the speed. using u, a and t as before, we use the equation v = u + at. since u = 0, this reduces to v = at = (270 m/s)(0.02 s) = 5.4 m/s. and when speed is constant, we know distance travelled is speed times time. we know it travels at 5.4 m/s for 0.030 s, so during that time it travels (5.4 m/s)(0.03 s) = 0.162 m. so the total distance it travels, and therefore the reach of the tongue, is 0.054 m + 0.162 m = 0.216 m = 21.6 cm.

So they will become stable and others become stable