BITSAT 2024 Shift 1 Paper

To determine the work done by the lower block on the upper block, follow these steps:
Calculate Maximum Possible Acceleration:
The maximum acceleration the upper block ( 1 kg ) can experience without sliding off is due to static friction:
amax=µg=1m∕ s2
where µ is the coefficient of friction and g is the acceleration due to gravity.
Calculate Common Acceleration:
The applied force is distributed over the total mass ( 3 kg ) of the system, so the acceleration a is:
a=‌

F

m‌total ‌

=‌

0.5

3

=‌

0.5

3

m∕ s2
Check for Relative Motion:
Since a<a‌max ‌, the blocks will move together without slipping.
Calculate the Force of Friction:
The force of friction acting from the lower block to the upper block is:
f=m‌upper ‌‌‌⋅a=1⋅‌

0.5

3

=‌

1

6

N
Calculate the Work Done by Friction:
The work done by this friction force over a displacement of 3 meters is:
W=f×s=‌

1

6

×3=0.5J
Thus, the work done by the lower block on the upper block for a displacement of 3 meters is 0.5 J .