1. How much energy is dissipated in braking a 1200-kg car to a stop from an initial speed of 30 m/s?
2. 1/2 mv(final)^2 - 1/2 mv(initial)^2
3. 1/2 x 1200 x 0^2 - 1/2 x 1200 x 30^2 = 540000J
is this right ? cheers
given the initial velocity, it is acceleration due to gravity that determines how long the ball stays in the air. Thus, to find the time of flight we deal with the vertical part of the motion. Since the ball starts at and returns to ground level, the displacement in the y direction is zero. The...
1. this is straight out of PHYSICS 8e by cutnell and johnson
chapter 3 page 70
there are two solutions to this equation. one is given by (14 m/s + 1/2 (-9.8 m/s ^2)t = 0 or t = 2.9s
what i can't seem to work out is how did they get t = 2.9s from those calculations
2. y = Voyt +...
1. The density of the liquid flowing through the horizontal pipe in the drawing is 1200 kg/m3. The speed of the fluid at point A is 7.5 m/s while at point B it is 11 m/s. What is the difference in pressure, PB – PA, between points B and A?
2. Bernoulli's Equation P1 + 1/2 pv1^2 + pgy1 = P2 + 1/2...
ohhhhh that makes total sense =)
the difference between the path of the initial and final position being the definition of displacement
the displacement then is actually 800m east from the initial position (1600 - 800, (800 being halfway back of 1600) as you stated)
thanks heaps =)
ok so I've worked out that average velocity = 800m/300s which gives us 2.66 east (rounded up to 2.7) but i don't totally understand why I've used 800m, how is 800m the displacement, i thought the displacement would have been the 1600m in the east direction not 800 back to the west ?
hey guys I am very new to physics and its just not making sense at the moment and i know this is a very simple question but i just don't get how to get the velocity ! I've worked out the average speed but i have no idea what the next step is to get the velocity, any hints would be very much...