Physics Problems and Solutions for Students | Desklib

Q1)
B
C
This is because when the engine is started it will go down but in a deep space, there will be no
force to stop the rocket from moving sideways, therefore when the engine will provide a constant
acceleration then the trajectory of the rocket will be parabolic, and therefore it will be expected
for the trajectory not to be linear
Q2)
a) The conveyor belt is moving with constant speed towards right and a box is placed on it,
therefore when the box is placed the velocity of the box was zero in the direction of the
conveyor belt so there was a relative motion in between conveyor belt and the box, the
force of kinetic friction will act on direction of motion of belt of belt which accelerates
the box in the direction of motion of belt and the box will begin to gain velocity in the
direction of motion of belt.
At the time when velocity of belt and box becomes equal in the right direction then the
box sits on the conveyor belt without slipping and force of static friction keeps the box
fix at one place on the belt
b) Immediately after the box is placed on the belt, box moves to the left side, on the box the
weight of the box acts downwards, normal force on the box acts upward and force up
kinetic friction fk acts in right direction
Yes there is frictional force that acts on the right direction
c) At this stage, weight of the acts downwards, normal force equals to the weight of box acts
upwards a force of static friction act on the box in the right direction.

Q3)
a) Fnet = ma
m = mass of the object
a = acceleration of the object
For a single pulley system, the tension will be acting upwards directions while the weight
of the piano will be acting in the downward direction.
The net force will be equal to
Fnet = T – mg
T = tension in the rope
Mg = mass of the piano
At the point one holds the piano , a= 0 m/s2
Substituting 0 m/s2 for a in the equation Fnet = ma
Fnet = m(0 m/s2)
= 0
Substitute 0 for Fnet = T – mg
0 = T – mg
T = mg
b) For double pulley system
Tension in the rope is acting in upward directions and weight of the piano of the piano in
the downward direction
The net force acting on the piano – rope system
Fnet = 2T – mg
Substituting for Fnet in the equation above
0 = 2T – mg
T = mg/2

Q4)
Fx = max => mgsinƟ – friction = ma
 Mgsin300 = may
Fy = may
Mgcos300 – N = may
Constraints
Friction = 0
ay = 0
mgsin300 = max
ax = gsin300= 9.8 * ½ = 4.9 m/s2
Mgcos300 = - N = 0
Mgcos300 = N
N = 10 * 9.8 * 0.866
N = 84.87 kg/s2
N = 84.87 N
Therefore, acceleration n of block = 4.9 m/s2 and Normal force acting on box – 84.87 kgm/s2
(b) given d = 10 m
Initial velocity , u = o m/s
Acceleration, a = gsinƟ = 4.9 m/s2
Now consider the equation
d = ut + ½ at2
10 = 0 + ½ *4.9 * t2