a) Speed is a scalar quantity because it only has magnitude (how fast an object is moving) and no direction.

Here's the solution to your question: a) Speed is a scalar quantity because it only has magnitude (how fast an object is moving) and no direction. b) When the horse runs, chemical energy stored in its muscles is converted into kinetic energy (energy of motion) and thermal energy (heat due to friction and metabolic processes). c) Horse hoofs wear faster on a rough racecourse because the rough surface increases the friction between the hoofs and the ground. This increased friction causes more abrasion and wear. d) The horse maintains a speed of 16 m/s for the last 20 s. To find the time it takes to run a distance of 160 m at this constant speed, we use the formula: Time = DistanceSpeed Step 1: Identify the given values. Distance = 160 m Speed = 16 m/s Step 2: Substitute the values into the formula. Time = 160 m16 m/s Step 3: Calculate the time. Time = 10 s The time it takes the horse to run a distance of 160 m is 10 s. e) In the last 20 s, the horse maintains the same speed of 16 m/s. This means its velocity is constant, and therefore its acceleration is zero. According to Newton's First Law of Motion, if an object's acceleration is zero, the net force acting on it is also zero. f) For the last 20 s, the horse maintains a constant speed. In a distance-time graph, constant speed is represented by a straight line with a positive gradient. Since the problem asks for a sketch for the last 20 s, we assume this is the period after it has reached its constant speed. The graph would show a linear increase in distance over time. g) In the first 10 s of Fig. 1.2, the speed of the horse increases from 0 m/s to 16 m/s. The curve shows that the gradient is decreasing, meaning the acceleration is decreasing over this period. The horse is accelerating, but its acceleration is not constant; it is getting smaller as time progresses. Send me the next one 📸