Question

What is the approximate acceleration of the block
and trolley system shown in the figure above, if
the coefficient of kinetic friction between the trol-
ley and the surface is 0.04?
(1) 1 m/s2
(2) 20 m/s2
(3) 10 m/s2
(4) 15 m/s2
​

Answer 1

Explanation:

Kinetic friction

Kinetic coefficient of friction (μ

k

=0.04)

30−T=m

1

a ( or ) 30−T=3×a→(1)

T−f

k

=m

2

a→(2)

m

1

& m

2

→ masses of block & trolley

f

k

=μ

k

R and R=m

2

×g

=20×g

⇒20×10=200 N

f

k

=0.04×200=8 N

T−8=20×a→(3)

adding (1) & (3)

30−8=23×a ( or ) a=

23

22

( or ) a=0.956 ms

−2

T=20×a+8

T=27.1 N

→ Required answer