top of a building. Is there enough information given answer 16. A ball from rest
ID: 1771590 • Letter: T
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top of a building. Is there enough information given answer 16. A ball from rest is dropped from the to find the time required for the ball to reach the bottom? Explain and describe your (2 points) 17. Consider the following equation. Identify and explain every term in the equation. Express the same equation for an object under free fall (2 points) 18. Is the below statement correct? If not explain what is wrong (2 points) "Kinematic equations are valid only for constant velocity and constant acceleration motion. They cannot be used for changing acceleration." 19. For an object under free fall, draw a diagram for the motion and label only the "forces" acting on the object (2 points) 20. A ball of mass 10 gm is thrown upwards with an initial velocity 10 m/s. Now answer the following questions (14 points) a. Is the object under free-fall? Explain your answer b. Draw a diagram and label all the parameters of the motion c. Identify all the parameters in the problem along with the sign convention. d. What is the acceleration on the object? Explain e. At its maximum height, what will be its velocity? What does this velocity f. g. correspond to? How long (in seconds) will the object take to reach its maximum height? What is the maximum height the object can reach? 21. A ball is dropped from the top of a building. The final velocity when it reaches the ground is 24 m/s. Now answer the following questions (6 points) Draw a diagram for the motion and identify all the parameters along with the sign convention a. b. Identify the best equation to calculate the time required for the ball to reach the ground c. Identify the best equation and calculate the height of the building 22. A ball is thrown vertically upwards with a speed of 27.5 m/s. Now answer the following question (6 points) Draw a diagram for the motion and identify all the parameters along with the sign convention How long will it take for the ball to hit the ground after it reaches its highest point? What is its velocity when it return to the level from which it started? a. b. c.Explanation / Answer
16)No the information is not sufficient. In order to calculate the time to reach the ground we need height of the building.
We know from eqn of motion,
S = ut + 1/2 at^2
S = H ; u = 0 ; a = g
H = 1/2 g t^2 => t = sqrt (2H/g)
So the height of the building is required for the calculate the time taken to reach the ground.
17) xf = xi + vi t + 1/2 at^2
xf is the final height/distance reached by an object/projectile.
xi is in the intial height.
t is the time taken to cover the distance.
a is the acceleration with which the object is moving.
18)The given statement is wrong.Its not like they are valid for constant velocity and acceleration only.
constant velocity implies zero acceleration. All the three equations has acceleration into it. At any point of time they enable us to calulate the distance travelled by the object, the final velocity and the acceleration and times also.
19)An object under free fall always experience a signle force only, that the force due to gravity which is equal to its weight. Its always directed downwards.
There may be a drag force due to air also but its always explicitly defined incase it has got significant affect and is to be considered. It acts upwards for a freely falling object.
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