Other Physics Answers

A ball is thrown horizontally from a building 63.0 m high with a speed of 25.0 m/s. Find the (a)vertical and horizontal components of the ball's initial velocity, (b) time flight, (c) distance from the foot of the building where the ball will strike the ground, and (d) velocity when the ball will strike the ground.

Eight boys are equally spaced about a pushball and each exerts a force upon it toward the center, as shown. Each boy in position 1, 3, and 7 exerts a force of 70 N, and the rest of the boys exert 50 N each. What force is needed to keep the ball at rest? *

A screw jack, 25% efficient and having a screw of pitch 0.4cm is used to raise a load through a certain height. If I’m the process the handle turns through a circle of radius 40cm, calculate the

i) velocity ratio of the machine

ii) The mechanical advantage of the machine

iii) Effort required to rise a load of 1000N with the machine. (take π = 3.14)

Draw a block and tackle system of pulleys with a velocity ratio of 5 . A block and tackle with a velocity ratio of 5 is used to raised a mass of 25 kg through a vertical distance of 40 cm at a steady rate. If the effort is equal to 60 N, determine

a)the distance moved by the effort;

b)the work done by the effort in lifting the load;

c)the loss in energy involved in operating the machine.

Show that the sound wave intensity I can be written in terms

of the frequency f and displacement amplitude dm in the form, I = 2pi

vf ^2s^2 m.

A particle moves from x1 = 5 cm to x2 = 20 cm in 5 s. The average velocity of the particle during this time interval is

You are standing on a very slippery icy surface and throw a 1 kg football horizontally at a speed of 7.3 m/s. What is your velocity (in m/s) when you release the football? (Assume your mass is 66 kg and that the positive direction is the direction of motion of the football. Indicate the direction with the sign of your answer.)

A particle moves along the x axis according to

the equation x = 2.00 + 3.00 t - 1.00

, where x is in

meters and t is in seconds. At t = 3.00 s, find (a) the

position of the particle, (b) its velocity, and (c) its acceleration.

Serving at a speed of 170 km/h, a tennis player hits the ball at a height of 2.5 m and an angle θ below the horizontal. The service line is 11.9 m from the net, which is 0.91 m high. What is the angle θ such that the ball just crosses the net? Will the ball land in the service box, whose out line is 6.40 m from the net?

1. A ball is thrown horizontally from the top of a 60.0-m building and lands 100.0 m from the base of the building. Ignore air resistance. (a) How long is the ball in the air? (b) What must have been the initial horizontal component of the velocity? (c) What is the vertical component of the velocity just before the ball hits the ground? (d) What is the velocity (including both the horizontal and vertical components) of the ball just before it hits the ground?