Presentation on theme: "5-I TEM MCQ S IN K INEMATICS. 1) What do you call the total length traveled by an object in a given time? a. Distance b. Displacement c. Speed d. Acceleration."— Presentation transcript:
Explanation # 1: Total length is the total distance d traveled by an object. Given time is the time elapsed t to travel a certain distance. If you divide distance by time, you get speed v. In symbols, v = d/t
Explanation # 2: In the physical world, the slowing down or coming to a stop of an object is called negative acceleration or, more appropriately, deceleration. It happens when the final velocity of an object is less than its initial velocity.
Explanation # 3: An object that moves with a constant speed has zero acceleration. You can prove this mathematically by using the equation: You can clearly infer from the equation that if v i and v f are the same, the acceleration becomes zero, no matter how long the object travels. a = (v f -v i )/t
Explanation # 4: Time must be expressed in seconds. By converting, 1.5 minutes is equal 90 seconds. Since v = d/t, and substituting the values: v = d/t 20 ms -1 = d / (90s) d = (20 ms -1 ) (90s) d = 1800 m = 1.8 km
Explanation # 5: In the physical world, deceleration means slowing down of an object’s motion. In the problem, v i = 400m/s, v f = 0, and t = 45 s. Since a = (v f -v i )/t, and substituting the values: a = (v f -v i )/t a = (0 m/s – 400 m/s) / 45 s a = 8.88 m/s 2