Physics Help? I have a couple of homework questions. This is standard Physics.?

Question

1. A rifle bullet with a muzzle speed of 360 m/s is fired directly into a special, dense material that stops the bullet in 28 cm. Assuming the bullet's deceleration to be constant, what is its magnitude? __ m/s^2

2. A 60 kg gymnast hangs vertically from a pair of parallel rings.

a If the ropes supporting the rings are attached to the ceiling directly above, what is the tension in each rope? __ N

b If the ropes are supported so that they make an angle of 40º with the ceiling, what is the tension in each rope? ___N

3. A 1500 kg automobile travels at a speed of 85 km/h.

a What is its kinetic energy? __ J

b What is the net work required to bring it to a stop? __ J

Answer 1

1. Constant deceleration, the velocity follows the equation
v(t)=v0-a*t
and the distance follows the equation
s(t)=v0*t-.5*a*t^2
v(t)=0 when s(t)=.28 m
so
.28=360*t-.5*a*t^2
and
0=360-a*t
a=360/t
plug into s
.28=360*t-.5*360*t
.28*2/360=t
a=360^2/(.28*2)

2.
a. 60*9.8/2

b. 60*9.8/2*(1/cos(40))

3.
using KE=.5*m*v^2
1km=1000m
1 hr=3600 sec
1 km/hr=1/3.6
KE=.5*1500*/(3.6*2)



the KE is equal to the work required to stop .


j

Answer 2

ok sick help you. First comprehend the assumption of a tension. A tension is a version in velocity (movment) of a physique having a mass in fact F(tension)=Mass x Acceleration in many situations written as F=ma No tension is in newtons and 10 newtons are akin to approximately a million kg.Now going particularly in the direction of answering your question. The deceleration (destructive acceleration) of the swimmer is the replace in velocity /time taken i.e from a million.25 to 0 protecting a distance of two.20 m to locate the time taken use this equation v^2 =u^2 + 2as or very final velocity (0)^2 = preliminary velocity (a million.25)^2 + 2(acceleration) * distance(2.20m) and make acceleration the subject of the formulation. After working the acceleration in basic terms enter acceleration (a) in F= m (mass of the swimmer x acceleration and you have have been given it made) i did no longer artwork it for you yet i guided you so which you will learn the way no longer the respond.