Question

1.13g plastic stopper is attached to a 0.93-m string. The stopper is swung in a horizontal circle, making one revolution in 1.18s(period T). Find the tension force(equivalent to the centripetal force)exerted by the string on the stopper? (V=2(pie)r/T)?

2. A football is thrown at 30 m/s(speed of release Vi)is 30 m/s, and its angle of release is 40 degree with respect to the horizontal. What is its horizontal velocity Vix? And what is its vertical velocity Viy? (Using trigonometry)


3. In a long jumper's motion, the highest point of the trajectory Y is 1.8m, the horizontal velocity at this point Vx is 7.2m/s. What is the full range of this long jump motion?(notice that the trajectory for this motion is symmetrial)

4. A car traveling at 30 m/s lost control and fell off a 50-m cliff by a projectile trajectory into a flat valley. Where should the car land on the flat bottom of the valley?




(( Note I was absent but my teacher couldn't explain anything to me so help please?))

Answer 1

When you post serveral questions on the same post, without any work or indication of what you need, your chances go down.

a. Tension=mass*velocity^2/r
and your teacher is just too easy with this hint: (V=2(pie)r/T)

b. vix=speed*cosTheta
vertical speed=speed*sinTheta

c.time to fall:
h=1/2 g t^2
t= sqrt (2*1.8/9.8)
range=2t*7.2 m

d. time to fall:
50=1/2 g t^2
t= sqrt(100/9.8)
distance= 30m/s * time

Answer 2

So for the first one I got 0.78.

The second 23 horizontal and 20 vertical.

The third I got 8.64

And fourth I got 96

??