A boy weighs 360 N on Earth.
i) What would be his approximate weight on the moon?ii) What is the reason for your answer?
i) Weight of the body on the moon is one-sixth of the weight of the body on the earth.
Weight of the body = 1/6 x Weight of moon = 1/6 x 360 = 60 N
ii) W = mg
And, acceleration due to gravity on moon as one-sixth that on the earth. Therefore, weight on the moon is also one-sixth of the earth.
A body is acted upon by a force. State two conditions under which the work done could be zero.
The two conditions are:
i) Displacement is zero.
ii) Angle between force and displacement is 90o.
A spring is kept compressed by a small trolley of mass 0.5 kg lying on a smooth horizontal surface as shown in the figure:
i) Define the term momentum.
ii) How is force related to the momentum of a body?
iii) State the condition when the change in momentum of a body depends only on the change in its velocity.
i) Momentum is defined as the product of mass and velocity of a body.
ii) Force = Rate of change in momentum
iii) When velocity of the body is much smaller than the velocity of light, then the mass is constant.
A body of mass 50 kg has a momentum 3000 kg m/s. Calculate:
i) the kinetic energy of the body.
ii) the velocity of the body.
Mass, m = 50 kg
Momentum, p = 3000 kg m/s
P = m × v
The refractive index of diamond is 2.42. What is meant by this statement?
It means tht the ratio of speed of light in air to the speed of light in diamond is 2.42.
Name the radioactive radiations which have the least penetrating power.
i) What is meant by refraction of light?
ii) What is the cause of refraction of light?
i) The deviation in the path of the light when it travels from one medium to the pther is called refraction of light.
ii) Speed of light is different from speed in different mediums.
i) Why is the mechanical advantage of a lever of the second order always greater than one?ii) Name the type of single pulley that has a mechanical advantage greater than one.
i) The mechanical advantage of a lever of the second order is always greater because the effort arm is greater than the load arm.
ii) Single movable pulley.
A stick partly immersed in water appears to be bent. Draw a ray diagram to show the bending of the stick. When placed in water and viewed obliquely from above.
The bending of the stick is as shown in the fig. below: