1) a projectile is launched at t=0 with initial speed with vi=11.2m/s at an angl

Question

1) a projectile is launched at t=0 with initial speed with vi=11.2m/s at an angle = 32 degrees above the horizontal. (a) what arev x and vy at the projectile's highest point? (b) find the time t at which the projectile reaches its maximum height. (c) find the heightH (answer to three decimal places)

a) vx=______ m/s and vy=______m/s

b) delta t=______s

c) H=______m

2) In free fall we assume the acceleration to be constant. not only is air resistance ignored, but the gravitational field strength is assumed to be constant. from what height can an object fall to the earth's surface such that the gravitaitonal field strength changes less that 0.895% during the fall?

_____km

3)

4) you are driving your car along a country road at a speed of 21.3 m/s as you come over a crest of a hill you notice a farm tractor 35.4m ahead of you on the road moving in the same direction as you in 10 m/s you immediatly slam on your breaks and slow down with a constant accleration of 7.00 m/s^2. a) will you hit the tractor before you stop? b) how far will you travel before you stop or collide witht the tractor? c) if you stop, how far is the tractor infront of you when you finally stop?

5) an airplane is traveling from new york to paris a distance of 5.81 x 10^3 km neglect the curvature of the earth. a) if the crusing speed of the airplane is 350 km/h how much time will is take the airplane to make a round-trip on a calm day. b) a steady wind blows from new york to paris at 63.2 km/h how much time will the round trip take? c) how much time will it take if there is a cross wind at 62.5 km/h? (answers in hours)

6) objects with the fowwling masses are initallly at rest, a force F acts on each of them for a time T. rank the magnitudes of the finale velocites of the objects from smallest to largest at time T.

a) 2m

b)6m)

c) m/3

d) 5m

e)m/5

Explanation / Answer

1)a)vx=11.2cos32

=9.498

vy=0 (since at highest point no vertical rise)

b)t=vy/g

=usin32/g

=0.6056 s

c)height=0.5gt^2

=0.5*9.8*(0.6056)^2

=1.797 m

2)let the height be x.so,

0.85*GM/R^2=GM/(R+x)^2

or 0.85/(6371)^2=1/(6371+x)^2

or x=539.32 km

3)a)distance=0.017m

so,

v^2=u^2+2as

or 40^2=2*a*0.017

or a=47058.8 m/s^2

b)let the time taken be t.so,

t=v/a

=40/47058.8

=8.5*10^-4 s

6)m/5 > m/3 > 2m > 5m > 6m

5)a)time taken=d/v

=5.81*10^3/350

=16.6 hr

b)time taken=5.81*10^3/(350+63.2)

=14.061 hr

c)effective speed=(350^2+62.5^2)^0.5

so time=5.81*10^3/(350^2+62.5^2)^0.5

=16.3415 hr

4)relative velocity=21.3-10

=11.3 m/s

so,

time=v/a

=21.3/7

=3.04

so,

distace covered=11.3*3.04-0.5*7*3.04^2

=2m

no i will stop before i hit

the tractor is 2m in from of me after i stop

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