Download M. Prakash Academy IX Science Practice 1) A stone is thrown

M. Prakash Academy
IX Science Practice
1) A stone is thrown vertically upward from the ground such that it reaches the height of 5 m. If
it is thrown at time t=0, determine the time after which it returns back to the ground. Express
your answer in second. [2]
2) A car travels between two towns A and B connected by a
v (km/h)
straight road. The variation of the velocity of the car with
distance along the road is given in the graph. The distance is 32
expressed in km along the horizontal axis and velocity is
expressed in km/h along the vertical axis. Calculate the time
d(km)
taken by the car to cover the distance between A and B.
0
4
8
Express your answer in minute. [30]
3) A ball is dropped from the top of a building. At the same instant another ball is thrown
vertically upward from the ground level with a speed of 12 m/s. The balls collide 2 seconds
later. The height of the building, expressed in meters, is [24].
4) A ball is thrown vertically upwards from the terrace of a building with speed 10 m/s. The ball
is thrown such that it can fall to the ground. It is observed that the ball falls to the ground 5
seconds later. Calculate the height of the building in meters. [75]
5) A body starts from rest with constant acceleration and its velocity after 10 s is 35 m/s.
Calculate the displacement of the body from t=8 to t=10 s. Express your answer in meter.
[63]
6) An elevator in a building is known to ascend or descend with initial acceleration of 1.5 m/s2.
A man takes a weighing machine and a 25 kg object with him in the elevator. He places the
object on the machine and starts the elevator. The elevator begins to move up. Calculate the
weight registered by the machine during the initial acceleration. Express your answer in
kilogram and to the nearest integer. [29]
7) A raindrop of mass 1 gram falls through air with constant acceleration. Its velocity increases
by 6 m/s every second. The frictional force exerted by air on the drop is expressed as F x 10-4
Newton. What is the value of F? [40]
8) A parachutist is descending with constant velocity of 8
A
Wind speed = 6 m/s
m/s. When at a distance of 80 m from the ground (point
8 m/s
A), she encounters a strong horizontal wind blowing 80 m
with velocity 6 m/s. The wind carries the parachutist
Ground
with it in the horizontal direction as she descends.
Calculate the time taken by the parachutist, from point A, to land on the ground. Express
your answer in second. [10]
9) A small object of mass 150 g is lying on smooth, horizontal table. Two
N
forces of equal magnitude
begin to act on the object. Both forces
are horizontal and act at angle 600 with each other as shown. Calculate
600
N
2
the acceleration of the object. Express your answer in m/s . [20]
150 g
10) Consider the “Horse and Cart” story in which a pony with mass 80 kg pulls the cart. The
tension in rope connecting the cart to the pony is found to be 100 N. If the pony begins to
move with acceleration of 2 m/s2, calculate the force F with which the pony pushes
backwards on the ground. If F is expressed in Newton and written as k Χ 10, write the value of
k in your bubble sheet. [26]
11) The adjoining velocity-time graph presents
velocity (m/s)
motion of a particle from time t = 0 s to t = 1 s. 20
Read the graph carefully and calculate the average
0.6
1
velocity of the particle in interval t = 0 to t = 1s.
0.5
0.7
time (second)
Express your answer in m/s. [3]
40
12) As shown in the figure, two blocks of mass 5kg
91 N
5 kg
8 kg
and 8kg are kept on a smooth, horizontal
surface and are connected by a rod. The rod is
made up of a material which is rigid and extremely light so mass of rod can be neglected. A
force of 91 N is applied on the 5kg block. Compute the force exerted by the rod on the 8kg
block. Express your answer in Newton. Neglect friction. [56]
13) A body of mass 10 kg is moving with
5 m/s
velocity 5 m/s along a smooth
35 m/s
horizontal surface. Due to some
B 4 kg
A
10 kg
internal action it explodes into two
pieces A and B. Piece B, of mass 4 kg,
Before Explosion
After Explosion
is found to be moving with velocity 35
m/s in the forward direction. calculate the speed of piece A. Express your answer in m/s. [15]
14) The term marathon for long distance running races originates in a historical event.
Pheidippides ran from Marathon to Athens in 490 B.C. to bring the news of victory of the
ancient Greeks over Persians. Historians suggest that Pheidippides ran at 23 rides per hour.
Ride, stadium and plethron are ancient Greek units of measuring length. 1 ride equals 4
stadia and 1 stadium equals 6 plethra. In terms of modern units, 1 plethra is about 31 meter.
Using this information calculate Pheidippides’ speed. Express your answer in km/hr by
rounding off to the nearest integer. [17]
15) A man of mass 40 kg, standing on smooth ground, is wearing skates so that there is no
friction between his feet and the ground. He pulls on a rope tied to a wall with a constant
force of 100 N. If his initial distance from the wall is 100 m plus 125 cm, calculate the time
he will take to reach the wall. Express your answer in second. [9]