Physics Answers

a vehicle is travelling at 70km/h and a child ran onto the road 120m in front. can the driver avoid the child.

For the system of two blocks on a frictionless double incline where the blocks are linked by an inextensible massless string over a frictionless pulley (see figure),

(a). Draw the free body diagram for m₁ and m₂.

(b). Express the equations of motion of the two blocks using Newton's Laws

(c). Prove that for the system to be in equilibrium

Some of the electrons which are emitted at low velocities from a hot wire (cathode) go through a small hole in a plate that is at a potential of 1000volts with respect to the cathode. What is the velocity of the electrons when they are passing through the hole? A second plate is parallel to the first and 20cm beyond it and is at a potential of -2000volts with respect to the cathode. Describe the motion of electrons in the region between the two plates.

From a lengthof 31m a ball dropped on a horizontal ground rebound with half

of its velocity with which it hits the ground

What is the velocity with which it hits the ground?

What is the time interval between the first and thesecond impacts of the ball

with the ground?

An intensity of a sound wave is measured to be 1.87×104 W/m2 at position A, 120 m away from the source of this sound. A worker at position B, 308 m away from the source hears the sound.

What is the sound level 120 m way from the source?

The best leaper in the animal kingdom is the puma, which can jump to a height of 3.7 m when leaving the ground at an angle of 45°. With what speed must the animal leave the ground to reach that height?

If the rail has a cross sectional area of 30cm2, the force of compression on the railway will be

Its uses to calculate wavelength of light by Diffraction grating 

Diffraction grating:

Definition, principle, background theory, procedures, it uses to calculate wavelength of light.

A heat pump cycle delivers energy by heat transfer to a dwelling at a rate of 11.7 kW. The coefficient of performance of the cycle is 2.8. Evaluating electricity at $0.10 per kW ⋅ h, determine the cost of electricity during the heating season when the heat pump operates for 1800 hours.