English
Karnataka Board PUCPUC Science Class 11

The benches of a gallery in a cricket stadium are 1 m wide and 1 m high. A batsman strikes the ball at a level one metre above the ground and hits a mammoth sixer. - Physics

Advertisements
Advertisements

Question

The benches of a gallery in a cricket stadium are 1 m wide and 1 m high. A batsman strikes the ball at a level one metre above the ground and hits a mammoth sixer. The ball starts at 35 m/s at an angle of 53° with the horizontal. The benches are perpendicular to the plane of motion and the first bench is 110 m from the batsman. On which bench will the ball hit?

Short Note

Solution

Given:
Angle of projection of the ball, α = 53°
Width and height of the bench = 1 m
Initial speed of the ball = 35 m/s
Distance of the first bench from the batsman = 110 m
The batsman strikes the ball 1 m above the ground.
Let the ball land on the nth bench.
∴ y = (n − 1)    ...(i)
And,

\[x = 110 + n - 1 = 110 + y\]

\[\text{ Now } , \]

\[y = x\tan\alpha - \left( \frac{g x^2 \sec^2 \alpha}{2 u^2} \right)\]

\[ \Rightarrow y = \left( 110 + y \right)\left( \frac{4}{3} \right) - \frac{10 \times \left( 110 + y \right)^2 \left( \sec^2 53^\circ \right)}{2 \times \left( 35 \right)^2} \]

\[ = \frac{440}{3} + \frac{4}{3}y - \frac{250 \left( 110 + y \right)^2}{18 \times \left( 35 \right)^2}\]

\[ = \frac{440}{3} + \frac{4}{3}y - \frac{250 \left( 110 + y \right)^2}{18 \times {35}^2}\]

Solving the above equation, we get:
y = 5
⇒ n − 1 = 5
⇒ n = 6
The ball will hit the sixth bench of the gallery.

shaalaa.com
  Is there an error in this question or solution?
Chapter 3: Rest and Motion: Kinematics - Exercise [Page 53]

APPEARS IN

HC Verma Concepts of Physics Vol. 1 [English] Class 11 and 12
Chapter 3 Rest and Motion: Kinematics
Exercise | Q 44 | Page 53

RELATED QUESTIONS

A player throws a ball upwards with an initial speed of 29.4 m s–1.

  1. What is the direction of acceleration during the upward motion of the ball?
  2. What are the velocity and acceleration of the ball at the highest point of its motion?
  3. Choose the x = 0 m and t = 0 s to be the location and time of the ball at its highest point, vertically downward direction to be the positive direction of x-axis, and give the signs of position, velocity and acceleration of the ball during its upward and downward motion.
  4. To what height does the ball rise and after how long does the ball return to the player’s hands? (Take g = 9.8 m s–2 and neglect air resistance).

A ball is dropped from a height of 90 m on a floor. At each collision with the floor, the ball loses one tenth of its speed. Plot the speed-time graph of its motion between t = 0 to 12 s.


In a projectile motion the velocity 


A train starts from rest and moves with a constant acceleration of 2.0 m/s2 for half a minute. The brakes are then applied and the train comes to rest in one minute. Find the total distance moved by the train .


A train starts from rest and moves with a constant acceleration of 2.0 m/s2 for half a minute. The brakes are then applied and the train comes to rest in one minute. Find the position(s) of the train at half the maximum speed.


A bullet travelling with a velocity of 16 m/s penetrates a tree trunk and comes to rest in 0.4 m. Find the time taken during the retardation.

 

A driver takes 0.20 s to apply the brakes after he sees a need for it. This is called the reaction time of the driver. If he is driving a car at a speed of 54 km/h and the brakes cause a deceleration of 6.0 m/s2, find the distance travelled by the car after he sees the need to put the brakes on.

 

Complete the following table:

Car Model Driver X
Reaction time 0.20 s
Driver Y
Reaction time 0.30 s
A (deceleration on hard braking = 6.0 m/s2) Speed = 54 km/h
Braking distance
a = ............
Total stopping distance
b = ............
Speed = 72 km/h
Braking distance
= ...........
Total stopping distance
d = ............
B (deceleration on hard braking = 7.5 m/s2) Speed = 54 km/h
Breaking distance
e = ...........
Total stopping distance
f = ............
Speed 72 km/h
Braking distance
g = .............
Total stopping distance
h = ............

 


A healthy youngman standing at a distance of 7 m from a 11.8 m high building sees a kid slipping from the top floor. With what speed (assumed uniform) should he run to catch the kid at the arms height (1.8 m)?


An NCC parade is going at a uniform speed of 6 km/h through a place under a berry tree on which a bird is sitting at a height of 12.1 m. At a particular instant the bird drops a berry. Which cadet (give the distance from the tree at the instant) will receive the berry on his uniform?


A ball is dropped from a height of 5 m onto a sandy floor and penetrates the sand up to 10 cm before coming to rest. Find the retardation of the ball is sand assuming it to be uniform.


A ball is thrown horizontally from a point 100 m above the ground with a speed of 20 m/s. Find the time it takes to reach the ground .


In a soccer practice session the football is kept at the centre of the filed 40 yards from the 10 ft high goalposts. A goal is attempted by kicking the football at a speed of 64 ft/s at an angle of 45° to the horizontal. Will the ball reach the goal post?


A popular game in Indian villages is goli which is played with small glass balls called golis. The goli of one player is situated at a distance of 2.0 m from the goli of the second player. This second player has to project his goli by keeping the thumb of the left hand at the place of his goli, holding the goli between his two middle fingers and making the throw. If the projected goli hits the goli of the first player, the second player wins. If the height from which the goli is projected is 19.6 cm from the ground and the goli is to be projected horizontally, with what speed should it be projected so that it directly hits the stationery goli without falling on the ground earlier? 


A staircase contains three steps each 10 cm high and 20 cm wide (in the following figure). What should be the minimum horizontal velocity of a ball rolling of the uppermost plane so as to hit directly the lowest plane ? 


A swimmer wishes to cross a 500 m wide river flowing at 5 km/h. His speed with respect to water is 3 km/h.  Find the shortest possible time to cross the river.


An aeroplane has to go from a point A to another point B, 500 km away due 30° east of north. A wind is blowing due north at a speed of 20 m/s. The air-speed of the plane is 150 m/s. Find the time taken by the plane to go from A to B.


Two friends A and B are standing a distance x apart in an open field and wind is blowing from A to B. A beat a drum and B hears the sound t1 time after he sees the event. A and B interchange their positions and the experiment is repeated. This time B hears the drum timer after he sees the event. Calculate the velocity of sound in still air v and the velocity of wind u. Neglect the time light takes in travelling between the friends. 

 

It is a common observation that rain clouds can be at about a kilometre altitude above the ground.

  1. If a rain drop falls from such a height freely under gravity, what will be its speed? Also calculate in km/h. ( g = 10 m/s2)
  2. A typical rain drop is about 4mm diameter. Momentum is mass x speed in magnitude. Estimate its momentum when it hits ground.
  3. Estimate the time required to flatten the drop.
  4. Rate of change of momentum is force. Estimate how much force such a drop would exert on you.
  5. Estimate the order of magnitude force on umbrella. Typical lateral separation between two rain drops is 5 cm.

(Assume that umbrella is circular and has a diameter of 1 m and cloth is not pierced through !!)


A man is standing on top of a building 100 m high. He throws two balls vertically, one at t = 0 and other after a time interval (less than 2 seconds). The later ball is thrown at a velocity of half the first. The vertical gap between first and second ball is +15 m at t = 2 s. The gap is found to remain constant. Calculate the velocity with which the balls were thrown and the exact time interval between their throw.


Share
Notifications

Englishहिंदीमराठी


      Forgot password?
Use app×