Search & Filtering
A horseshoe is heated in a blacksmith's furnace until it glows blue/white. Does the mass of the horseshoe change? If so, explain how and why. b) If a spring is stretched to twice its equilibrium length, has the spring's mass been altered in the process? If so, explain how and why.
You are standing still on a spacecraft that is ravelling toward the Sun and 0.25c. a) How fast are you moving relative to a person that is on Earth observing your spacecraft's motion? b) You get out your radar gun and point it at the Sun. What speed do you measure for sunlight, given that your spacecraft is travelling toward the Sun at 0.25 c? c) At what speed, relative to c, do relativistic effects become significant?
A special prototype model airplane of mass 400g has a control wire 8cm long attached to its body. the other end, of the control line is attached to a horizontal circle with its wings horinzontal. the wire OX is inclined at 60 degree to the horizontal and fixed to a point O and X takes 4s to fly once round its circular path. calculate; (i) the tension T in the control wire (ii) the upward force on X due to the air
A lamp is mapped 12v,24w.how many joules does it consume in an hour and what is the current it passes?
You are using a wheel and axle as a simple machine. You applied a force of 30 lb to the rim
of the wheel so that it can lift a load of 240 lb. The diameters of the wheel and axle are 3 feet
and 4 inches, respectively. Determine the efficiency of the machine
You are working as a letter sorter in the Post Office. Postal regulations require that employees’
footwear must have a minimum coefficient of static friction of 0.5 on a specified tile surface.
You are wearing athletic shoes for which you do not know the coefficient of static friction. In
order to determine the coefficient, you imagine that there is an emergency and start running
across the room. You have a co-worker time you, and find that you can begin at rest and move
4.23 m in 1.20 s. If you try to move faster than this, your feet slip. Assuming your acceleration
is constant, does your footwear qualify for the postal regulation?
The center of gravity of a 50g meter stick is at 51 cm and the stick is supported at 70 cm. Where must an 80g object be hung in order to have equilibrium?
A pulley system as shown in figure 4 has an ideal mechanical advantage of 5 and is used to
lift a load of 1000 lb. If the effort moves 10 ft, how far does the load move? If this work was
done in 15 s, what horsepower was developed? If the machine was 80 % efficient, how much
effort would be needed to lift the load?
The IMA of the pulley system shown in figure 3 is 4, how far must the applied force move if
the load moves 1 ft? If the load weighs 200 lb and the efficiency of the system is 90 %, what
must be the applied force?
The pitch of a jackscrew shown in figure 2 is 0.3 cm and has a lever arm of 60 cm length. What
force at the end of the lever arm will raise a load of 190 kg if the efficiency of the machine is
12 %?
