Q. There is a stream of neutrons with a kinetic energy of . If the half life of neutron is second, what fraction of neutrons will decay before they travel a distance of ? Given mass of neutron .

KCET KCET 2022 Report Error

A

B

C

D

Solution:

From the given kinetic energy of the neutrons, we first calculate their velocity. Thus

or
with this speed, the time taken by the neutrons to travel a distance of is,

The fraction of neutrons decayed in time second is, also,
.

Questions from KCET 2022

1. A truck of mass Ton is moving with a speed of . Sand is poured at the rate of per minute. How much force is needed to keep it moving with the same speed?

2. A horizontal force is applied on a block of weight to hold against a vertical wall. The minimum value of force needed to hold the block if the coefficient of friction of the surface is

3. A bird is inside a wire cage hung from a spring balance. The spring balance reading is when the bird is flying and when it is at rest inside the cage. Which of the following is correct?

4. 6. An ideal heat engine gives out heat at to have a of efficiency. The temperature of the source is

5. In an auditorium absorption co‐efficient of an open window is

Physics Most Viewed Questions

1. If and respectively denote energy and gravitational constant, then has the dimensions of:

NEET 2021 Physical World, Units and Measurements

2. The de Broglie wavelength of an electron moving with kinetic energy of is nearly

NEET 2020 Dual Nature of Radiation and Matter

3. A car starts from rest and accelerates at At , a ball is dropped out of a window by a person sitting in the car. What is the velocity and acceleration of the ball at ? (Take

NEET 2021 Motion in a Straight Line

4. A wheel with metallic spokes each long is rotated with a speed of in a plane perpendicular to a magnetic field of . The induced emf between the axle and rim of the wheel will be,

NEET 2020 Electromagnetic Induction

5. A barometer is constructed using a liquid (density What would be the height of the liquid column, when a mercury barometer reads ?
(density of mercury

NEET 2020 Mechanical Properties of Fluids

Latest Updates