Question 5.35 A block of mass 15 kg is placed on a long trolley. The coefficient of static friction between the block and the trolley is 0.18. The trolley accelerates from rest with 0.5 m s–2 for 20 s and then moves with uniform velocity. Discuss the motion of the block as viewed by (a) a stationary observer on the ground, (b) an observer moving with the trolley.
Chapter Laws Of Motion Page 113
Answers
mass of block ( Mb) = 15 kg
Coefficient of friction between the block and the trolley (u) = 0.18
acceleration of the trolley = 0.5 m/s^2
Block is placed on the trolley , so force applied on the block by the trolley
F = Mb*a
= 15 * 0.5 N
= 7.5 N this is reaction force applied by the trolley on the block , so its direction is opposite of motion of the trolley .
hence limiting friction oppose the motion of the block .
we know ,
body will be rest when limiting friction is greater then applied force on the block by the trolley .
now,
Limiting Friction (f) = uN
= 0.18 * Mb*g
= 0.18 * 15* 9.8
= 26.46 N
here, f> F , so static friction adjusr itself .
hence, block will remain at rest on the trolley .
after 20 sec trolley moves with uniform velocity . so, acceleration and force applied by trolley on the block will be zero. it means there is no frictional force act on the block .
e.g block appear at rest relative to trolley to a STATIONARY observer on the ground .
(b) A observer moving with the trolley with an acceleration. it means observer will be non-inertial frame of reference .hence, Newton's law invalid here and also law of inertia doesn't hold good. so, motion of block can't be observed by him .
hence, block will be rest relative to observer in this situation.
____________________________________________
Answer:
Explanation:
mass of block ( Mb) = 15 kg
Coefficient of friction between the block and the trolley (u) = 0.18
acceleration of the trolley = 0.5 m/s^2
Block is placed on the trolley , so force applied on the block by the trolley
F = Mb*a
= 15 * 0.5 N
= 7.5 N this is reaction force applied by the trolley on the block , so its direction is opposite of motion of the trolley .
hence limiting friction oppose the motion of the block .
we know ,
body will be rest when limiting friction is greater then applied force on the block by the trolley .
now,
Limiting Friction (f) = uN
= 0.18 * Mb*g
= 0.18 * 15* 9.8
= 26.46 N
here, f> F , so static friction adjusr itself .
hence, block will remain at rest on the trolley .
after 20 sec trolley moves with uniform velocity . so, acceleration and force applied by trolley on the block will be zero. it means there is no frictional force act on the block .
e.g block appear at rest relative to trolley to a STATIONARY observer on the ground .
(b) A observer moving with the trolley with an acceleration. it means observer will be non-inertial frame of reference .hence, Newton's law invalid here and also law of inertia doesn't hold good. so, motion of block can't be observed by him .
hence, block will be rest relative to observer in this situation.
Hope it is helpful.
Please me as brainlist