# Crossbow acceleration

This is a two step problem:

a) In deep space (no gravity), the bolt (arrow) of a crossbow accelerates at 193 m/s2 and attains a speed of 124 m/s when it leaves the bow. For how long is it accelerated?

b) What speed will the bolt have attained 3.6s after leaving the crossbow? Answer in m/s

I correctly figured out that it is accelerated for .642 s. But I don't quite understand what happens afterwards. Since there is no gravity, doesn't the acceleration continue? I multiplied 193 by 3.6 but the answer is wrong.

Integral
Staff Emeritus
Gold Member
RECALL:
F=ma

No force, No acceleration. As soon as the bolt seperates from the sting the force ends.

HallsofIvy
Homework Helper
This is a two step problem:

a) In deep space (no gravity), the bolt (arrow) of a crossbow accelerates at 193 m/s2 and attains a speed of 124 m/s when it leaves the bow. For how long is it accelerated?
Do you know what acceleration means? Initial speed was 0 m/s, final speed was 124 m/s. (124- 0)/x sec= 193 m/sec2. What is x?

b) What speed will the bolt have attained 3.6s after leaving the crossbow? Answer in m/s
You were given the acceleration! final speed = initialspeed (0)+ acceleration* time as long as it does accelerate- after that, constant speed!

I correctly figured out that it is accelerated for .642 s. But I don't quite understand what happens afterwards. Since there is no gravity, doesn't the acceleration continue? I multiplied 193 by 3.6 but the answer is wrong.
Yep! you were told that it accelerates to a final speed of 124 m/s. After that, no acceleration= constant speed.