a)A projectile of mass m = 7.98 kg is fired straight upward twice, both times at

Question

a)A projectile of mass m = 7.98 kg is fired straight upward twice, both times at initial speed vo = 68.2 m/s. The first time there is no air friction, and the projectile reaches height ho; the second time the air dissipates Elost = 4435 J of energy as the projectile rises, and it rises to height h. Find ho - h, the difference betwen the height the projectile reaches without friction and the height it reaches with friction.

<<ANSWER IS NOT 180.6>>

b) Assume friction is negligible. Three identical stones are thrown from the roof of a building with the same initial speed vo. One is thrown at angle ? above the horizontal; one is thrown at angle ? below the horizontal; the third is thrown outward along the horizontal. Which statement is true about each of the following quantities:

- vf, the speed with which the stones hit the ground
- x, the distance the stones hit the ground from the base of the building
- t, the time the stones take to hit the ground

The t's are different, but all the vf's and x's are the same

The t's and x's are all different, but all the vf's are the same

The vf's and t's are different, but all the x's are the same

They all have different vf, t and x ---> <<this is not a answer!!!!!>>

The vf's and x's are different, but all the t's are the same

The vf's are different, but all the t's and x's are the same

They have different x's, but all the vf's and t's are the same

They all have the same vf, t and x

Explanation / Answer

Here is the answer for the following question rate of water lifted=2.3kg/s Change in potential energy of water/s=mgh Change in kinetic energy=0.5mv2 Total change in energy=mgh+0.5mv2=103.5W

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