Mechanics | Relativity Answers

Power delivered to a body varies as P=3t^2. Find out the change in kinetic energy of a body from t=2 sec to t=4 sec.

Sand drops at the rate of 2000 kg/min. from the bottom of a hopper onto a belt conveyor moving horizontally at 250 m/min. Determine the force needed to drive the conveyor, neglecting friction

A stone thrown from ground level returns to the same level 4 s after. With what speed was the stone thrown? Take
g=10ms−2

The displacement of a particle along the X-axis is given as
x=5t2+1
, where x is in metres and t in seconds. Calculate its instantaneous velocity 2 s.
46 m/s
40 m/s
20 m/s
25 m/s

A bullet is straight upward with a velocity of 100 m/s from the top of a building 100 m high. Find its maximum height above the ground
500 m
600 m
1000 m
300 m

The displacement of a particle along the X-axis is given as
x=5t2+1
, where x is in metres and t in seconds. Calculate its average velocity in the time interval between 2 s and 3 s.
21 m/s
40 m/s
46 m/s
25 m/s

An object is thrown upward from the edge of a building with a velocity of 20 m/s. Where will the object be 3s after it was thrown?

−22m
16m
22m

−16m

An observer can describe the motion of an object as "translational" if
the axes of the reference frame imagined to be attached to the object
x′
,
y′
and
z′
always remain parallel to the axes of his own reference frame
x
,
y
and
z
the object moves in a curved path in such a way that
x′
,
y′
and
z′
may rotate about their origin
O′
the motion of the object may not be represented by the motion of its centre of mass
all the constituent particles of the object undergo different displacements at the same time

Two vectors
a⃗
and
b⃗
have components, in arbitrary units,
ax=3.2
,
ay=1.6
,
bx=0.5
,
by=4.5
. Find the angle between
a⃗
and
b⃗

33o

28o

57o

62o

Which of the following correctly gives the direction of a vector product
c⃗ =a⃗ ×b⃗
?
If the right thumb points in the direction of
a⃗
and the other fingers point in the direction of
b⃗
, then the palm pushes in the opposite direction of
c⃗
If the right is held such that the curled fingers follow the rotation of
a⃗
into
b⃗
, then the extended right thumb points in the direction of
c⃗
If the left thumb points in the direction of
a⃗
and the other fingers point in the direction of
b⃗
, then the palm pushes in the direction of
−c⃗
The direction of retreat of the right-handed screw when turned from
a⃗
to
b⃗
through the smaller angle.