TMA2/PHY101

My TMA Home TMA Results My Pending TMA Quick Help TMA Quiz Questions TMA: TMA2/PHY101 score=9.50 PHY101 - Elementary Mechanics, Heat and Properties of Matter Mr. Ibanga Efiong (eibanga@noun.edu.ng ) 1 The rope shown in the figure attached hereto is wound around a cylinder of of mass 4.0 kg, radius 10cm and I=0020kgm2$$I=0.020kg{m}^2$$ , where I$$$$ is the moment of inertia about an axis along the cylinder axis. If the cylinder rolls without slipping, what the linear acceleration of its centre of mass? Click here to see exhibit 6.7m/s2$$\mathrm{}{}^{\mathrm{}}$$ 3.3m/s2$$\mathrm{}{}^{\mathrm{}}$$ 11.2m/s2$$\mathrm{}{}^{\mathrm{}}$$ 1.5m/s2$$\mathrm{}{}^{\mathrm{}}$$ 2 The frictional force between the block and the table is 20 N. If the moment of inertia of the wheel is 4.0kgm2$$\mathrm{}{}^{\mathrm{}}$$ , find how long it will take the block to drop 60cm$$\mathrm{}$$ after the system is released. Click here to see exhibit 7.37 s 1.34 s 3.71 s 4.22 s 3 The mass shown in the figure attached starts from rest and falls a distance h. Find the angular speed of the wheel in terms of the radius of the wheel and I, m and h. Click here to see exhibit ω=(2mgImb2−h)12$${\frac{\mathrm{}}{{}^{\mathrm{}}}}^{\frac{\mathrm{}}{\mathrm{}}}$$ ω=(2mgImb2+h)12$${\frac{\mathrm{}}{{}^{\mathrm{}}}}^{\frac{\mathrm{}}{\mathrm{}}}$$ ω=(2mghmb2−I)12$${\frac{\mathrm{}}{{}^{\mathrm{}}}}^{\frac{\mathrm{}}{\mathrm{}}}$$ ω=(2mghmb2+I)12$${\frac{\mathrm{}}{{}^{\mathrm{}}}}^{\frac{\mathrm{}}{\mathrm{}}}$$ 4 Find the equation for the simple harmonic motion shown Click here to see exhibit y=0.08sin(0.40πt−0.40π)$$\mathrm{}\mathrm{}\mathrm{}$$ m y=0.06sin(0.80πt+0.40π)$$\mathrm{}\mathrm{}\mathrm{}$$ m y=0.08sin(0.40πt+0.40π)$$\mathrm{}\mathrm{}\mathrm{}$$ m y=0.06sin(0.80πt−0.40π)$$\mathrm{}\mathrm{}\mathrm{}$$ m 5 For the simple harmonic shown, evaluate y$$$$ at t=1.35s$$\mathrm{}$$ Click here to see exhibit 0.034 m 0.023 m 0.047 m 0.012 m 6 When a 30-g mass is hung from the end of a spring, the spring stretches 8.0 cm. The same spring with a mass of 200 g at at its end is stretched 5.0 cm, released and allowed to oscillate on a frictionless horizontal surface. Find the frequency of the oscillation. 0.54 Hz 0.68 Hz 0.34 Hz 9.5 Hz 7 The system shown is an example of the Atwood's machine. What is the acceleration of the masses? Assume the the pulley is frictionless and the rope massless. Take g=9.8m/s2$$\mathrm{}{}^{\mathrm{}}$$ Click here to see exhibit 4.2m/s2$$\mathrm{}{}^{\mathrm{}}$$ 2.5m/s2$$\mathrm{}{}^{\mathrm{}}$$ 9.8m/s2$$\mathrm{}{}^{\mathrm{}}$$ 3.3m/s2$$\mathrm{}{}^{\mathrm{}}$$ 8 A boy intends to move an m-kg crate across the floor by applying a constant force P newtons on it.The coefficient of friction between the floor and the crate is μ$$$$ . Which of these is the best option for his task? Push the crate with P applied horizontally Push the crate with P inclined at an angle above the horizontal Pull the crate with P inclined at an angle above the horizontal Pull the crate with P inclined an angle below the horizontal 9 A boat propelled so as to travel with a speed of 0.50m/s in still water, moves directly (in a straight line perpendicular to the banks of the river assumed to be straight) across a river that is 60m wide. The river flows with a speed of 0.30m/s. How long in seconds does it take the boat to cross the river? 150 120 300 200 10 Which of the follwing statements is correcct? An object can have a constant velocity even though its speed is changing An object can have a constant speed even though its velocty is changing An object can have zero acceleration and eventually reverses its direction An object can have constant velocity even though its acceleration is not zero 11 Which of these is NOT a statement of Newton’s law of universal gravitation? gravitational force between two particles is attractive as well as repulsive gravitational force acts along the line joining the two particles gravitational force is directly proportional to the product of the masses of the particles gravitational force is inversely proportional to the square of the distance of the particles apart 12 How large an average force is required to stop a 1400-kg car in 5.0 s if the crate's initial speed is 25 m/s? 2000 N 3500 N 9000 N 7 000N 13 A 10-g bullet of unknown speed is shot horizontally into a 2-kg block of wood suspended from the ceiling by a cord. The bullet hits the block and becomes lodged in it. After the collision, the block and the bullet swing to a height 30cm above the original position. What was the speed of the bullet? (This device is called the ballistic pendulum). Take g=9.8ms−2$$\mathrm{}{}^{\mathrm{}}$$ 487 m/s 640 m/s 354 m/s 700 m/s 14 A 40-g ball travelling to the right at 30 cm/s collides head on with an 80-g ball that is at rest. If the collision is perfectly elastic, find the velocity of each ball after collision the first ball is going to the right at 10m/s while the other is going to the left at 20m/s the first ball is going to the left at 10m/s while the other is going to the right at 20m/s the first ball is going to the left at 20 m/s while the other is going to the right at 10 m/s the first ball is going to the right at 10 m/s while the other is going to the left at 10 m/s 15 A gun of mass M is used to fire a bullet of mass m. The exit velocity of the bullet is v. Find the recoil velocity of the gun Mv/m mv/M −Mv/m$$$$ −mv/M$$$$ 16 A 30,000-kg truck travelling at 10.0m/s collides with a 1700-kg car travelling at 25m/s in the opposite direction. If they stick together after the collision, how fast and in what direction will they be moving? 8.1 m/s in the direction of the truck's motion 12.3 m/s in the direction of the car's motion 24.2 m/s in the direction of the car's motion 17.6 m/s in the direction of the truck's motion 17 Sand drops at the rate of 2000 kg/min. from the bottom of a hopper onto a belt conveyor moving horizontally at 250 m/min. Determine the force needed to drive the conveyor, neglecting friction. 500 N 800 N 139 N 152 N 18 The exhaust gas of a rocket is expelled at the rate of 1300 kg/s, at the velocity of 50 000 m/s. Find the thrust on the rocket in newtons 6.5×107$$\mathrm{}{\mathrm{}}^{\mathrm{}}$$ 3.5×107$$\mathrm{}{\mathrm{}}^{\mathrm{}}$$ 7.6×107$$\mathrm{}{\mathrm{}}^{\mathrm{}}$$ 5.7×107$$\mathrm{}{\mathrm{}}^{\mathrm{}}$$ 19 A force of 2i⃗ +7j⃗ $$\mathrm{}\stackrel{}{}\mathrm{}\stackrel{}{}$$ N acts on a body of mass 5kg for 10 seconds. The body was initially moving with constant velocity of i⃗ −2j⃗ $$\stackrel{}{}\mathrm{}\stackrel{}{}$$ m/s. Find the final velocity of the body in m/s, in vector form. 5i⃗ +12j⃗ $$\mathrm{}\stackrel{}{}\mathrm{}\stackrel{}{}$$ 12i⃗ −5j⃗ $$\mathrm{}\stackrel{}{}\mathrm{}\stackrel{}{}$$ 10i⃗ −7j⃗ $$\mathrm{}\stackrel{}{}\mathrm{}\stackrel{}{}$$ 7i⃗ +10j⃗ $$\mathrm{}\stackrel{}{}\mathrm{}\stackrel{}{}$$ 20 Two trolleys X and Y with momenta 20 Ns and 12 Ns respectively travel along a straight line in opposite directions before collision. After collision the directions of motion of both trolleys are reversed and the magnitude of the momentum of X is 2 Ns. What is the magnitude of the corresponding momentum of Y? 6 Ns 8 Ns 10 Ns 30 Ns