Razmic Shirvanian Physics 2A Exam 2 Name Hasan seat 5 Problems (show work) lm.th

Question

Razmic Shirvanian Physics 2A Exam 2 Name Hasan seat 5 Problems (show work) lm.the Eig below the coefficient ofstatic friction between the 3 kg crate and the 350 incline is0.3 Q(l-2) 1. Draw free-body diagram for the crate and include all relevant forces. 2. What minimum force F must be applied to the crate perpendicular to the incline to prevent the crate from sliding down the incline? a. 24.4 N 32.1 N c. 15.23 N d. 56 N Askier starts from rest at the top ofanincline of height 20 m, as in the Eig below. The coefficient of kinetic 3. Find the Skier's speed at the bottom of the slope, point B? Use Work-Energy method a. 25.6 m/s 10.8 m/s c. 19.2 m/s d, 15,8 m/s 4.A0.012 kg bullet is fired horizontally into a 0.1 kg wooden block that is initially at rest on a frictionless horizontal surface and connected to a spring having spring constant The bullet becomes embedded in the block. If the bullet-block system com the spring by a maximum of 0.8 meter, what was the speed of the bullet at impact with the block? a. 345 m/s b, 273 m/s c. 182 m/s 134 m/s

Explanation / Answer

2. N = F + m g cos35

f = us N = 0.3F + 0.3 m g cos35

f = m g sin35

0.3F + 0.3 m g cos35 = m g sin35

F = m g (sin35/0.3 - cos35)

F = 32.1 N

Ans(b)

3. f = uk N = uk m g cos30

f= 0.21 x m x g x cos30 = 0.182 m g

Work done by friction + work done by gravity = change in KE

(-0.182 m g x 20 / sin30) + (m g 20) = m v^2 /2

v^2 /2 = (9.8 x 20) - (0.182 x 9.8 x 40) = 124.7

v = 15.8 m/s

ans(d)

4. Applying energy conservation for block-spring system,

m v^2 /2 = k x^2 /2

(0.1 + 0.0012) v^2 = (150) (0.8^2)

v = 29.3 m/s

now applying momentum conservation for the collision,

0.012 u = (0.1 + 0.012) (29.3)

u = 273.25 m/s

Ans(B)

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