I have several questions i will write all of them and give you my attempt at a solution, hope you can help me figure out what i am doing wrong, Thanks. Question 1: An air-track glider is attached to a spring. The glider is pulled to the right and released from rest at t=0.00 s. It then oscillates with a period of 11.4 s and a maximum speed of 52.9 cm/s. What is the glider's position at t=0.561 s? ==> ANSWER: T = 11.4s, Vmax = 52.9 cm/s I found out W (angular frequency) to = 0.175 pi = 0.55498 rad/s I also found A = 96.22 cm I used the equation X(t) = A cos ( w t ) X(0.561) = (96.22) cos ( 0.55498 x 0.561 ) = 96.2186 cm apparently this is the wrong answer....idk wat i am doing wrong though..any pointers? Question 2: A 543.0 g mass oscillates with an amplitude of 12.4 cm on a spring whose spring constant is 27.3 N/m. At t=0.00 s the mass is 4.36 cm to the right of the equilibrium position and moving to the right. Determine the phase constant. Use a cosine function to describe the simple harmonic motion. ==> ANSWER: Knowns: Xinitial = 4.36 cm A= 12.4 cm phase constant = cos^-1 ( Xinitial / A ) = cos^-1 (4.36 / 12.4) = 69.41 rad.....i think the units are radian rite? Again i got the wrong answer and idk where i went wrong.... Question 3: An object in simple harmonic motion oscillates with a period of 4.00 s and an amplitude of 9.79 cm. How long does the object take to move from x=0.00 cm to x=6.50 cm? ==> ANSWER: Knowns: T=4s A= 9.78m I found: w= 2pi/ T = 0.3927 rad/s Vmax = wA = 3.845 cm/s i have no idea how else to go about this question....any suggestions? Question 4: The velocity of an object in simple harmonic motion is given by v(t)= -(0.226 m/s)sin(15.0t + 2.00π), where t is in seconds. What is the first time after t=0.00 s at which the velocity is -0.110 m/s? ==> ANSWER: so since the equation for velocity is V(t) = -(Vmax) sin ( wt + phase constant ) we know that, Vmax = 0.226m/s W= 15 rad/s phase constant= 2pi rad i figured that the speed would be the same after a period....so i set out to find the period, T = 2pi / w = 0.4189s however that is the wrong answer, is there a flaw in my logic? Question 5: A 6.00 g spider is dangling at the end of a silk thread. You can make the spider bounce up and down on the thread by tapping lightly on his feet with a pencil. You soon discover that you can give the spider the largest amplitude on his little bungee cord if you tap exactly once every 7.00 s seconds. What is the spring constant of the silk thread. ==> ANSWER: m= 6g = 0.006 kg T= 7s k = ? I used the equation T = 2pi ( m / k )^(1/2) i rearranged it for k = (m 4pi) / T^2 = 1.54 x 10^-3 N/m again this was the wrong answer....plz help. Sry for posting so many questions but i didnt want to start many threads and the topic is all related its just that im studying for a test and these are the questions im stuck on....any help would be greatly appreciated..THANKS AGAIN!