Mechanics | Relativity Answers

A man leaves his house for an cycle ride.He comes back to his home after one hour after covering a distance of 2 km.then the displacement of a man is how much m.

Two waves 1 and 2 are present on a string:
(35mm) sin [(8.4m ) (15.7s ) ] 1 1
y1 x t
− − = −
(35mm) sin [(8.4m ) (15.7s ) ] 1 1
y2 x t
− − = +
(i) Write the expression for the resultant wave, y = y1 + y2 in the form of wave function
for a standing wave. (ii) Determine the x coordinates of the first two antinodes, starting at
the origin and progressing towards + x direction. (iii) Determine the x coordinate of the
node that is between the antinodes of part (ii).

In going from point A to B on the rough surface, the cyclist lost 200J of energy due to the
frictional force of the rough surface of the 10 m road. She started with an initial speed A v
at point A, arriving at point B with a speed of B v . The cyclist barely made it to the flat
part (point C) of the frictionless surface without pedaling


i) The speed of cyclist at point B, B v

ii) The speed of cyclist at point A, A v

iii) The coefficient of kinetic friction,mk , between the bike tires and the road.

A 95-kilogram student climbs 4.0 meters up a rope in 3.0 seconds. What is the power
output of the student?
(a) 1.3 ´102 W
(b) 1.2 ´103 W
(c) 3.8 ´102 W
(d) 3.7 ´103 W
(e) n.o.t.a.

A force of 250 N is applied to a hydraulic jack piston that is 5.0E-3 m in radius. If the
piston which supports the load has a radius of 0.05 m, approximately how much mass can
be lifted by the hydraulic jack? Ignore any difference in height between the pistons.
(a) 255 kg
(c) 800 kg
(e) 6300 kg
(b) 500 kg
(d) 2550 kg

At t = 0 seconds, a ball is thrown straight upwards from the edge of 50m-high building,
with a velocity of 10 m/s. If there is no air resistance, the ball hits the ground after:



(b) In the expression E=1\2 C (L\T)^2 ,L is measured in meters, t is measured in seconds and
E is measured in (Newton . meter), what is the unit of the symbol C , and what does it
physically represent?
a) Newton.meter; it represents force
b) Kg; it represents mass
c) m/s; it represents speed
d) m/s; it represents velocity
e) None of the above

A boy standing still throws a ball at an angle 600, with the horizontal as shown in the
figure below. At the moment the boy releases the ball, he ran eastwards to catch the ball.
If the boy caught the ball in exactly 2 seconds at the same height from which he threw it.
Neglect the effect of air resistance or wind on the ball.

a) What is the magnitude of the initial velocity, |v0|, with which the boy threw the ball?

b)With what average velocity (magnitude and direction) must the boy run in order to
catch ball at the point shown?

c) What is the speed of the ball when the boy catches it?

file:///Users/123456/Desktop/Document6.htm

A boy kicks his football (soccer ball) with an initial speed of 30 m/s at an angle 45o
above the horizontal aiming to hit a 20 m-tall post which is 25 m away from him.
Neglecting air resistance, find: a) with what velocity will he hit the post, b) where
exactly (x, y) will he hit it?

A free falling body has a constant acceleration of 9.8m/s2. This means that:
A. the body falls 9.8 m during each second
B. the body falls 9.8 m during the first second only
C. the speed of the body increases by 9.8 m/s during each second
D. the acceleration of the body increases by 9.8 m/s2 during each second
E. the acceleration of the body decreases by 9.8 m/s2 during each second

A ball is in a free fall. Its acceleration is:

A. downward in both ascent and descent
B. downward during ascent and upward during decent
C. upward during ascent and downward during decent
D. upward during both decent and descent
E. downward during all times except at the very top, when it is zero