Question
and two...
A small spacecraft faces in the +x-direction, and moves only along the x-axis during this problem. The spacecraft has two rocket thrusters that can be used to accelerate it along the x-axis: one facing backward, to create positive acceleration, and one facing forward, to create negative acceleration. (Ignore all friction in this entire problem.) The following graph represents the spacecraft's acceleration as a function of time: Suppose that at t= 15 s, the spacecraft's velocity is: v = -15 m/s. What was the spacecraft's initial velocity, v0 at time t = 0? Show your work and/or explain your reasoning. A baseball player on the Boston Red Sox team is playing in Boston's Fenway Park stadium. During his turn at bat, he hits a baseball with an initial velocity of 35.0 m/s at an angle of 45.0 degree above the horizontal. (Assume that the baseball field is level, and that there is no air resistance.) Calculate the vertical and horizontal components, v0x and v0y, of the initial velocity of the baseball. Show your work. What maximum vertical displacement (above the level at which the ball was hit) docs the ball reach? Show your work. Suppose that the player is attempting to hit a "home run" by hitting the baseball over the famous "Green Monster" fence in left field. The ball happens to be aimed toward a point on the fence where the fence is 10.0 meters high (above the level at which the ball was hit) and is located at a horizontal distance of 100. meters away from the player. Will the ball clear the top of the fence? Show your work and/or explain your reasoning.
Explanation / Answer
A.Let the initial velocity be v0.With a constant acceleration of -2.5m/s2,the final vel=-15.So by v=u-at,we get u=22.5m/s
B.vx=35 cos 45=24.75m/s
vy=35 sin 45= 24.75m/s
At max height the only velocity is the horizontal component which is constant.
0= vy^2- 2X9.8x h,h=31.25m
we see if the time from one matches the other.
For 10m height,10=vyt-0.5x9.8xt^2,t=4.6,0.44
for 100m range,r=vxt,t=4.04.The time does not match any oif the previous two times,hence it wont clear the fence.Coz its not matching the height and distance at the same time.
