# Work, Energy and Power-Work-Energy Theorem (KVPY Stream SB-SX (Class 12 & 1st Year B.Sc.) Physics): Questions 1 - 3 of 4

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## Question number: 1

» Work, Energy and Power » Work-Energy Theorem

Appeared in Year: 2011

MCQ▾

### Question

Two plates each of the mass m are connected by a massless spring as shown.

A weight W is put on the upper plate which compresses the spring further. When W is removed, the entire assembly jumps up. The minimum weight W needed for the assembly to jump up when the weight is removed is just more than –

### Choices

Choice (4) Response

a.

b.

c.

d.

## Question number: 2

» Work, Energy and Power » Work-Energy Theorem

Appeared in Year: 2012

MCQ▾

### Question

In one model of the election, the mass of electron me is thought to be a uniformly charged shell of radius R and total charge e, whose electrostatic energy E is equivalent to its mass me via Einstein’s mass energy relation E = mec2. In this model, R is approximately – (me = 9.1 × 10-31kg, c = 3 × 108 ms-1, magnitude of the electron charge = 1.6 × 10-19 C)

### Choices

Choice (4) Response

a.

b.

c.

d.

## Question number: 3

» Work, Energy and Power » Work-Energy Theorem

Appeared in Year: 2012

MCQ▾

### Question

A stream of photons having energy 3 eV each impinges on a potassium surface. The work function of potassium is 2.3 eV. The emerging photo-electrons are slowed down by a copper plate placed 5 mm away. If the potential difference between the two metal plates is 1V, the maximum distance the electrons can move away from the potassium surface before being turned back is

### Choices

Choice (4) Response

a.

3.5 mm

b.

5.0 mm

c.

1.5 mm

d.

2.5 mm

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