(20%) Problem 4: You throw a rock off of a cliff in the horizontal direction wit

Question

(20%) Problem 4: You throw a rock off of a cliff in the horizontal direction with a velocity, v. One second later you throw an identical rock with the same velocity, v, in the horizontal direction What is true about the distance between the two rocks beginning after you throw the second one? Grade Summary Deductions Potential The distance between the rocks will decrease as time passes Whether the distance between the rocks will increase or decrease depends on the velocity v with which they are rown It depends on the hcight of the cliff The distance between the rocks will increase as time passes The distance between the rocks will stay the same as time passes It cannot be determined 0% 100% Submissions Attempts remaining:5 (20% per attempt) detailed view Submit Hint I give up! Hints: 1 % deduction per hint. Hints remaining: 3 Feedback: 1% deduction per feedback

Explanation / Answer

Both rocks are thrown with the same horizontal velocity, there is no acceleration in horizontal direction. So the

Ditance travlled is linear

Distance travelled by first stone X = vt

Ditance travleled by the second stone X’ = vt’

X-X’ = vt- vt’

X = v(’-t’)

Since t’ = t -1

X = v(t -(t-1))

X = v since v is constant The horizontal distance does not change with time

Both rocks have no velocity in vertical direction.

Their inital speed u = 0

The acceleration dur to gravity acts in vertical direction

Distance ttravelled by first stone

Y = ut + ½gt2

Y = ½gt2

Distance ttravelled by second stone

Y’ = ut’ + ½gt’2

Y’= ½gt’2

Y - Y’ = ½gt2-½gt’2

Y = ½gt2-½g(t-1)2

Y = ½gt2-½g(t-1)2

Y = ½gt2-½g(t2-2t + 1)

Y =½g(1 -2t)

So the vertical distance is directly proportional to time.

With the increase in time the vertical distance increase

Since the resultant postion

S2 = X2 + Y2

The actual distance between the rocks will increase as time passes

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