Mechanics | Relativity Answers

Which of the follwing statements is correcct?
An object can have a constant velocity even though its speed is changing
An object can have a constant speed even though its velocty is changing
An object can have zero acceleration and eventually reverses its direction
An object can have constant velocity even though its acceleration is not zero

A man walks
5.0m
due east and then
10.0m
N30oE
. Find his resultant displacement.
13.7 m,
N15oE
14.6 m,
N20oE
10.0 m,
N15oE
14.6m,
N70oE

Given three vectors
a⃗ =−i⃗ −4j⃗ +2k⃗
,
b⃗ =3i⃗ +2j⃗ −2k⃗
,
c⃗ =2i⃗ −3j⃗ +k⃗
, calculate
a⃗ ⋅(b⃗ ×c⃗ )

−6
6
9

−9

Which of the following equations is not dimensionally consistent? the symbols have their usual meaning.

s=ut−gt2

Ft=mv−m0

−kx+F0sinωt=ma

ω2=ω20+αθ

What are the dimensions of pressure gradient?

MLT−2

ML−2T−2

ML3T−2

M−2L2T−3

If s is distance and t is time, what must be the dimensions of a and b in the equation
s=asin(bt)
?

[a]=[L]−1
,
[b]=[L]−1

[a]=[T]−1
,
[b]=[L]

[a]=[L]
,
[b]=[T]−1

[a]=[L]2
,
[b]=[T]−2

Which of the following is the correct unit of k in the equation of a damped harmonic oscillator given as
−bv−kx=ma
, where b is the damping factor and all the symbols have their usual meaning?

kgms−2

kgs−1

kgms−1

kgs−2

A man leaves the garrage in his house and drives to a neighbouring town which is twenty kilometres away from his house on sight-seeing. He returns home to his garrage two hours after. What is his average velocity from home in km/h?

Which of the following quantities is an example of a vector or cross product?

momentum

work

density

torque

A child pulls on a 90 N wagon with a force of 100 N at 37^o
above the horizontal. Calculate the acceleration of the wagon. Assume
that friction is negligible.
(a)8.7m/s^2
(b)9.6m/s^2
(c)3.4m/s^2
(d)7.1m/s^2