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001 (part 1 of 3) 10.0 points In deep space (no gravity), the bolt (arrow) of a crossbow accelerates at 139 m/s 2 and attains a speed of 127 m/s when it leaves the bow. For how long is it accelerated? Answer in units of s

 

002 (part 2 of 3) 10.0 points What speed will the bolt have attained 3.5 s after leaving the crossbow? Answer in units of m/s

 

003 (part 3 of 3) 10.0 points How far will the bolt have traveled during the 3.5 s? Answer in units of m

 Nov 6, 2014

Best Answer 

 #1
avatar+33665 
+5

001.

Use v = u + at  (assuming constant acceleration applied by the bowstring).

127 = 0 + 139t

t = 127/139 s

$${\mathtt{t}} = {\frac{{\mathtt{127}}}{{\mathtt{139}}}} \Rightarrow {\mathtt{t}} = {\mathtt{0.913\: \!669\: \!064\: \!748\: \!201\: \!4}}$$

t ≈ 0.9137 s

 

002.

Since it doesn't accelerate after it leaves the bow and there is nothing to retard it in space, it continues with the same speed: v = 127 m/s.

 

003.

distance = speed*time

distance = 127*3.5 m

$${\mathtt{distance}} = {\mathtt{127}}{\mathtt{\,\times\,}}{\mathtt{3.5}} \Rightarrow {\mathtt{distance}} = {\mathtt{444.5}}$$

distance = 444.5m

.

 Nov 6, 2014
 #1
avatar+33665 
+5
Best Answer

001.

Use v = u + at  (assuming constant acceleration applied by the bowstring).

127 = 0 + 139t

t = 127/139 s

$${\mathtt{t}} = {\frac{{\mathtt{127}}}{{\mathtt{139}}}} \Rightarrow {\mathtt{t}} = {\mathtt{0.913\: \!669\: \!064\: \!748\: \!201\: \!4}}$$

t ≈ 0.9137 s

 

002.

Since it doesn't accelerate after it leaves the bow and there is nothing to retard it in space, it continues with the same speed: v = 127 m/s.

 

003.

distance = speed*time

distance = 127*3.5 m

$${\mathtt{distance}} = {\mathtt{127}}{\mathtt{\,\times\,}}{\mathtt{3.5}} \Rightarrow {\mathtt{distance}} = {\mathtt{444.5}}$$

distance = 444.5m

.

Alan Nov 6, 2014

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