## F.Sc ICS Notes: Physics XI: Chapter 3 Motion and Force Numerical Problems

__A helicopter is ascending vertically at the rate of 19.6 m/s when it is at a height of 156.8 m above the ground, a stone is dropped. How long does the stone take to reach the ground?__

**Numerical Problem 3.1:**__Using the following data, draw a velocity-time graph for a short journey on a straight road of a motorcycle.__

**Numerical Problem 3.2:**velocity 0 10 20 20 20 20 0

time 0 30 60 90 120 150 180

use the graph to calculate:

(a) The initial acceleration

(b) The final acceleration

(c) The total distance traveled by the motorcyclist.

**Numerical Problem 3.3:****A proton moving with the speed of 1 * 10(7)m/s passes through a 0.02cm thick sheet of paper and emerges with speed of 2 * 10(6) m/s. Assuming uniform deceleration, find retardation and time taken to pass through the paper.**

__Two masses m1 and m2 are initially at rest with a spring compressed between them. What is the ratio of their velocities after spring has been released.__

**Numerical Problem 3.4:**__An amoeba of mass 1 * 10(-12)kg propels itself through water by blowing a jet of water through a tiny orifice. The amoeba ejects water with a speed of 1 * 10(-4)m/s at a rate of 1 * 10(-12)kg/s. Assume that the water is continuously replenished so that the mass of the amoeba remains the same.__

**Numerical Problem 3.5:**(a) If there were no force on amoeba other then the reaction force caused by the emerging jet, what would be the acceleration of the amoeba?

(b) If amoeba moves with constant velocity through water, what is force of surrounding water (exclusively of jet) on the amoeba?

__A boy places a fire cracker of negligible mass in an empty can of 40g mass. He plugs the end with a wooden block of mass 200g. After igniting the fire cracker, he throws the can straight up. It explodes at the top of its path. If the block shoots out with a speed of 2m/s, how fast will the can be going?__

**Numerical Problem 3.6:**__An electron (m = 9.1 * 10(-31)kg) traveling at 2 * 10(7)m/s undergoes a head on collision with a hydrogen atom (m = 1.67 * 10(-27)kg), which is initially at rest. Assume the collision to be perfectly elastic and motion to be a straight line, find the velocity of hydrogen atom.__

**Numerical Problem 3.7:**__A truck weighing 2500 kg and moving with a velocity of 21 m/s collides with stationary car weighing 1000 kg. The truck and the car move together after the impact. Calculate their common velocity.__

**Numerical Problem 3.8:**__Two blocks of masses 2 kg and 0.5 kg attached at two ends of a compressed spring. The elastic P/E stored in the spring is 10J. Find the velocities of the blocks if the spring delivers its energy to the blocks when released.__

**Numerical Problem 3.9:**__A football is thrown upward at an angle of 30 degree with respect to the horizontal. To throw a 40 m pass what must be the initial speed of the ball?__

**Numerical Problem 3.10:**__A ball is thrown horizontal from a height of 10m with velocity of 21m/s. How far off will it hit the ground and with what velocity?__

**Numerical Problem 3.11:**__A bomber dropped a bomb at a height of 490m when its velocity along the horizontal was 300 Km/h.__

**Numerical Problem 3.12:**(a) At what distance from the point vertically below the bomber at the instant the bomb was dropped, did it strike the ground?

(b) How long it was in air?

**Numerical Problem 3.13:****Find the angle of projection of a projectile for which its maximum height and horizontal range are equal.**

__Prove that for angle of projection, which exceed or fall short of 45 degree by equal amount the ranges are equal.__

**Numerical Problem 3.14:**__A submarine launched Ballistic Missile (SLBM) is fired from a distance of 3000km. If the earth were flat and the angle of launch is 45 degree with horizontal, find the time taken by Slbm to hit the target and the velocity with which the missile is fired.__

**Numerical Problem 3.15:**
Good job...

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