Laws of Motion Numerical's Solution

[2073 'D']

In a physics lab experiment, a $6\;kg$ box is pushed across a flat table by a horizontal force $(F)$.

(i) If the box is moving at a constant speed of $0.30\;m/s$ and the coefficient of kinetic friction is $0.12$, What is the magnitude of $F$?

(ii) If the box is speeding up with a constant acceleration of $0.18\;m/s^2$, what will be the magnitude of $F$? [Click here for Solution]

[2073 'C']

A little red wagon with mass $7\;kg$ moves in a straight line on a frictionless horizontal surface. It has an initial speed of $4\;m/s$ and then is pushed $3\;m$ in the direction of the initial velocity by a force of $10\;N$. Calculate the wagon's final speed and the acceleration produced by the force. [Click here for Solution]

[2072 'S']

A ball of mass $0.05\;kg$ strikes a smooth wall normally four times in $2$ seconds with a velocity of $10\;m/s$. Each time the ball rebounds with the same speed of $10\;m/s$. Calculate the average force on the wall. [Click here for Solution]

[2072 'C']

A $550\;N$ physics student stands on a bathroom scale in an elevator. As the elevator starts moving the scale reads $450\;N$. Draw a free body diagram of the problem and find the magnitude and direction of the acceleration of the elevator. [Click here for Solution]

[2071 S]
Suppose you try to move a carate by tying a rope qround it and pulling on the rope at angle of $30^0$ above the horizontal. What is the tension required to keep the crate moving with constant velocity? Assume weight of the crate $W = 500N$ and coefficient of dynamic fraction $\mu_k = 0.40$. [Click here for Solution]

[2071 'C']

A $650\;KW$ power engine of a vehicle of mass $1.5 \; * \; 10^5\; kg$ is rising on an inclined plane of inclination $1$ in $100$ with a constant speed of $60\;km/hr$. Find the frictional force between the wheels of the vehicle and the plane. [Click here for Solution]

[2070 'C']

A light rope is attached to a block with mass $4 \; kg$ that rests on a frictionless, horizontal surface. The horizontal rope passes over a frictionless pulley and a block with mass $m$ is suspended from the other end. When the blocks are released, the tension in the rope is $10\;N$. Draw free body diagrams and calculate the acceleration of either block and the mass $m$ of the hanging block. [Click here for Solution]

[Ans: $2.5 \; m/s^2$; $1.33\; kg$]

[2070 'S']

A car travelling with a speed of $15\;m/s$ is braked and it slows down with uniform retardation. It covers a distance of $88 \;m$ as its velocity reduces to $7\;m/s$. If the car continues to slow down with the same rate, after what further distance will it be brought to rest? [Click here for Solution]

[Ans: $24.5\;m$]

[2069 'A']:
A cricket ball of mass $145\; gm$ is moving with a velocity of $14\;m/s$ and is being hit by a bat, so that the ball is turned back with a velocity of $22\;m/s$. The force of blow acts on the ball for $0.015\; sec$. Find the average force exerted by the bat on the ball. [Click here for Solution]

[Ans: 348 N]

[2069 S]
What would be the acceleration of a block sliding down an inclined plane that makes an angle of 45° with the horizontal if the coefficient of sliding friction between two surfaces in 0.3? [Click here for Solution]

[2069 S]
A block is pushed 1.5 m along a horizontal tabletop with horizontal force of 2.4 N. If the frictional force between the surface in contact is 0.6 N, what is (i) work done on the block by the frictional force and (ii) the total work done on the block? [Click here for Solution]

[2062 S]

Calculate the acceleration of a block sliding down a slope of $30^0$. Given: coefficient of friction is 0.25 and $g = 9.8 m's^2$ [Click here for Solution]

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