Question #1 : The man shown below is pushing on a refrigerator that sits on a le
ID: 1528374 • Letter: Q
Question
Question #1 : The man shown below is pushing on a refrigerator that sits on a level floor. Assume the entire floor, including the portion under the man, is frictionless. The force exerted by the man has a magnitude of 112 N and the refrigerator has a mass of 198 kg. Use Newton's third law along with his second law to find the acceleration of the man. Assume he has a mass of 77 kg. (The force F is pointing in the positive direction. Indicate the direction with the sign of your answer.)
Question #2:Consider a map oriented so that the x-axis runs east-west (with east being the "positive" direction) and y runs north-south (with north "positive"). A person drives 24 km to the north, turns and drives 78 km to the east, and then turns north and drives for an unknown distance z. If his final position is 94 km from where he started, find z.
Question #3: Two crates are connected by a massless rope that passes over a pulley as shown in the figure below. If the crates have mass 35 kg and 82 kg, find their acceleration. If the system begins at rest, with the more massive crate a distance 11 m above the floor, how long does it take for the more massive crate to reach the floor? Assume the pulley is massless and frictionless.
Explanation / Answer
3.
Assuming m2 block moves downward, acceleration will be same for both blocks
Using the force balance:
m2*g - T = m2*a
T - m1*g = m1*a
Adding both equations:
m2*g - m1*g = m2*a + m1*a
a = (m2 - m1)*g/(m2 + m1)
a = (82 - 35)*9.81/(82 + 35) = 3.94 m/sec^2
distance traveled = 11 m
Using the equation:
s = u*t + 0.5*a*t^2
u = 0
t = sqrt (2*s/a)
t = sqrt (2*11/3.94) = 2.36 sec