Physics Test 8

Result

Physics Test 8

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Question 1
4 / -1

A cork is submerged in water by a spring attached to the bottom of a bowl. When the bowl is kept in an elevator moving with acceleration downwards, the length of spring–

A
increases

B
decreases

C
remains unchanged

D
none of these

Solution

Thrust decreases. When acceleration is downward.

Thrust = Vσ(g – a)

Therefore length of spring decreases.
Question 2
4 / -1

A monkey of mass 20 kg rides on a 40 kg trolley moving with constant speed of 8 m/s along a horizontal track. If the monkey jumps vertically to grab the overhanging branch of a tree, the speed of the trolley in the horizontal direction after the monkey has jumped off is -

A
8 m/s

B
1 m/s

C
4 m/s

D
12 m/s

Solution

Conserving momentum in the horizontal direction.

(40 + 20) kg*8 m/s = 40 * V m/s

where V m/s is the speed of the trolley after the monkey has grabbed the branch.

Hence, V = 12 m/s
Question 3
4 / -1

According to the first law of thermodynamics ΔQ = dU + ΔW, in an isochoric process –

A
ΔQ = dU

B
ΔQ = ΔW

C
ΔW = –dU

D
ΔW = ΔU

Solution

As the process is Isochoric; ΔW = 0

⇒ ΔQ = dU