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2. A 7.00-g bullet, when fired from a gun into a 1.00-kg block of wood held in a

ID: 1396653 • Letter: 2

Question

2. A 7.00-g bullet, when fired from a gun into a 1.00-kg block of wood held in a vise, penetrates the block to a depth of 8.00 cm. This block of wood is next placed on a frictionless horizontal surface, and a second 7.00-g bullet is fired from the gun into the block. To what depth will the bullet penetrate the block in this case? 3. The mass of the Earth is 5.97 x 24 kg, and the mass of the Moon is 7.35 x 10 22 kg. The distance of separation, measured between their centers, is 3.84 x10 m. Locate the center of mass of the Earth-Moon system as measured from the center of the Earth. 4. A small block of mass m1 -0.500 kg is released from W rest at the top of a frictionless, curve-shaped wedge of mass m2 E3.00 kg, which sits on a frictionless, horizontal surface as shown in Figure. When the block leaves the wedge, its velocity is measured to be 4.00 m/s to the right as shown in Figure b. (a) What is the velocity of the wedge after the block reaches the horizontal surface? (b) What is the height h of the wedge? mgo mag

Explanation / Answer

here,

mass of bullet , m = 0.007 kg

mass of block = 1 kg

when block is held in a vice,

final speed of bullet , V = 0

let the initial speed of bullet be u

depth , s = 0.08 m

by third equation of motion

a = (v^2 -u^2)/ 2 * s

a = - u^2 / 0.16 .....1

for the collison of block and bullet

let the final speed of buleet and block be vb

then using conservation of momentum

mass of bullet * speed of bullet = (mass of bullet + mass of box) * vb

0.007 * u = (0.007 + 1) * vb

vb = 6.99* 10^-3 * u

then after collison

initial speed of bullet = u

final speed of bullet , vb = 6.99* 10^-3 * u

accelration = - u^2 / 0.16

using newton third equation of motion

a = (v^2 -u^2)/ 2 * s

- u^2 / 0.16 = - ((6.99 * 10^-3)^2 * u^2 - u^2) /(2 * s)

s = 0.0799 m

the depth to which the bullet will penetrate this block is   0.0799 m