a)A projectile is fired from ground level at an angle of 40.0° above horizontal

Question

a)A projectile is fired from ground level at an angle of 40.0° above horizontal at a speed of 30.0 m/s. What is the speed of the projectile when it has reached a height equal to 50.0% of its maximum height?

b)A 1500-kg car accelerates from 0 to 25 m/s in 7.0 s with negligible friction and air resistance. What is the average power delivered by the engine? (1 hp = 746 W)

c)A 5.00-kg box slides 3.50 m across the floor before coming to rest. What is the coefficient of kinetic friction between the floor and the box if the box had an initial speed of 3.00 m/s?

Explanation / Answer

Maximum Height = u2sin2/(2g)

As u ang g remains Constant

therefore

Height Attained is directly proportional to sin2

Therefore

If Height reduces to 50% i.e,1/2 , herefore

sin2 reduces to 1/2 of the inital value

Therefore

sin reduces to 1/2 of the inital value

sin40 = 0.643

THererfore sin = 0.321

Therfore

= 18.74 degree

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