1. V = Vo + g*Tr = 0
The rise time(Tr) = 1/2 of time in air.
Vo = -g*Tr = 10(4/2)= 20 m/s
1. A stone throw from ground level returns to the same level 4 s after. With what speed was the stone throw? Take g = 10m per square.
2. A cart is moving horizontally along a straight line with constant speed ofb30 m/s. A projectile is fired from the moving cart in such a way that it will return to the cart after the cart has moved 80 m. At what speed (relative to the cart) and at what angle (to the horizontal) must the projectile be fired?
3. A 10-g bullet of unknown speed is shot horizontally into a 2-kg block of wood suspended from the celling by a cord. The bullet hits the block and becomes lodged in it. After the collision, the block and the bullet swing to a height 30cm above the original position. What was the speed of the bullet? (This device is called the ballistic pendulum). Take g= 9.8m/s square.
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