Physics Answers

A block of wood with length = 2.5 m, width = 0.5 m and height = 0.4 m. The density of water

is 1000 kg/m3. If the block is placed in the water, what is the buoyant force ?

A ship weighing 46 328 tons is lowered into water. What weight of water would it 

displace?

A spring (k = 3.5N/m) is attached to a superman doll of mass = 13.0 kg. If the action figure is hung from the ceiling by this spring, how much would the spring be stretched?

A copper rod of length 𝟒. 𝟓 𝒎 and cross-sectional area 𝟐. 𝟑𝟎 𝒄𝒎𝟐 is stretched by a heavy load of 𝟓𝟓𝟎 𝒌𝒈 attached to the rod’s lower end. What is the tensile stress in the rod and the final length after the elongation of the rod under the stress? Young’s modulus for copper is 𝒀 = 𝟏. 𝟐 𝒙 𝟏𝟎𝟏𝟏 𝑵𝒎−𝟐 .

The elastic limit of copper is 𝟏. 𝟓 × 𝟏𝟎𝟖 𝑵𝒎−𝟐 . If a copper wire is stretched by a load of mass 𝟖. 𝟓 𝒌𝒈 then find the minimum diameter of the wire within the elastic limit. 

What force is required to stretch a steel wire of cross-sectional area 𝟑 𝒄𝒎𝟐 to double it’s length? The Young’s modulus for steel is 𝒀 = 𝟐 × 𝟏𝟎𝟏𝟏 𝑵𝒎−𝟐 .

A wire of length 𝟑𝟓𝟎 𝒄𝒎 and radius 𝟏. 𝟓 𝒎𝒎 is stretched by load of 𝟏𝟎 𝒌𝒈 and increased by 𝟐. 𝟓% of the original length. Find the stress, strain and Young’s modulus of the material of the wire

The electric field vector E and the magnetic field vector H in

free space are given by £ = 50/p cos(10^6 t + /Bz) a V/m and

H =Ho/p cos( 10^6 t+Bz) ap A/m. Determine their respective

phasor forms and the constants Band Ho such that the fields

satisfy MaxwelJ's equations

Consider the two pucks shown in the figure. As they move towards each other, the momentum of each puck is equal in magnitude and opposite in direction. Given that v_{i, green} = 8.0 m/s,  and m_blue is 15.0% greater than m_green, what are the final speeds of each puck (in m/s), if 1/2  the kinetic energy of the system is converted to internal energy?

A proton, moving with a velocity of v_iî, collides elastically with another proton that is initially at rest. Assuming that after the collision the speed of the initially moving proton is 2.40 times the speed of the proton initially at rest, find the following.

(a) the speed of each proton after the collision in terms of v_i

initially moving proton__ x vi

initially at rest proton__ x vi

(b) the direction of the velocity vectors after the collision (assume that the initially moving proton scatters toward the positive y direction)

initially moving proton ___°relative to the +xdirection

initially at rest proton ___°relative to the +xdirection