Physics Answers

1. Draw the velocity-time graph of a car that starts with an initial velocity of 15km/hr and accelerates uniformly at 5ms-2 until it attains a maximum velocity of 50km/hr, it them maintains this speed for the next 2min. Use the graph to determine:

a. The total distance covered before it maintains the maximum velocity reached

b. The total distance covered in the entire journey

c. Average velocity

Assume 2 kg of hydrogen (Item B 28) are initially at 40 atm, 100 K. (a) If the hydrogen changes pressure to 1 atm without a change of temperature, find the changes of enthalpy and entropy. (b) If the hydrogen changes temperature to 35 K with no change of entropy, find the change of pressure and enthalpy.

a body of mass 0.1 kg drops from a height of 8m onto a hard floor bounces to a height of 2m. Calculate the momentum if the body is in contact with the floor for 0.1 seconds. What is the force exerted on the body (g=ms-²)

A child slides across a floor in a pair of rubber-soled shoes. The friction force acting on each foot is 20.0 N. The footprint area of each shoe sole is 14.0 cm2, and the thickness of each sole is 5.00 mm. Find the horizontal distance by which the upper and lower surfaces of each sole are offset. The shear modulus of the rubber is 3.00 MN/m2.

Write the phasors for the voltages and the currents marked in the circuit

shown in the figure.

Construct a phasor diagram showing Vs, IR, Ic, and IL.

2. 5H

m

IL

LR

Ic

500 Ω

20 µF

Vs (t) =500sin (100t) V

A 2.0 kg ice cube at 0 oC is placed in 22 kg of water at 25 oC. Determine the final

temperature of the mixture. [Given the specific heat of water, cw is 4186 J/kg oC and the

latent heat of fusion of water, Lf is 3.33 ×105 J/kg]

A spacecraft with a proper length of 300 m takes 0.75 ms to pass an Earth-based observer. Determine the speed of the spacecraft as measured by the Earth observer.

Represent graphic the force of Weight of a man. Is the Weight force of a man on Earth the same if the man is sitting vertical or horrizontal?

An ice glider, that has a mass of 1640 kg, is initially moving at 20 m/s NW. A wind accelerates the glider at 2.5 m/s? 20° E of N for eight second. Then the wind shifts to 48°E of N accelerating the glider at 1.8 m/s for 11 seconds. 1) What is the glider's initial kinetic energy? 2) What is the glider's velocity at t= 8 s? 3) How much energy did the wind transfer to the glider during the 8 s? 4) What was the glider's velocity after the 11s the second wind gust was active? 5) How much energy did the wind transfer to the glider during the 19s? 6) What was the glider's average speed from t = 0 s to t = 19 s? 7) What was the glider's displacement from t = 0 s to t = 19 s? 8) What was the glider's average velocity from t = 8stot=198? 9) What was the glider's final kinetic energy? 10) A student contends that the glider will have the largest force at t = 19 s since it has the most kinetic energy at that time. Is this contention reasonable? Explain.

An object of mass moves round a circle of radius 6 m if the if the period of motion is π calculate the force towards the centre