1) As a raindrop falls through the atmosphere, its speed initially changes as it falls toward the Earth. Before the raindrop reaches its terminal speed, the magnitude of its acceleration _______. A. increases B. decreases C. stays constant at zero D. stays constant at 9.8 m/s^2 E. stays constant at a value not equal to zero nor 9.8 m/s^2 2) The position vector of a particle is given by r?(t) = 2tî + 3t^2? where r? is measured in metres and t is measured in seconds. Given that the mass of the particle is 0.5 kg, calculate the linear momentum of the particle at t = 2 s. A. (12?) kg m/s B. (î + 6?) kg m/s C. (2î + 6?) kg m/s D. (4î + 12?) kg m/s 3) A 200 g block is placed on a rough horizontal surface as shown in the figure below. A 4-N force is applied on the block at an angle of 30° with the horizontal axis. Given that the static coefficient of friction between the block and the surface is 0.9 and the kinetic coefficient of friction is 0.7, what is the value of the frictional force acting on the block? [diagram: block on surface, force F at 30° above horizontal] A. 1.8 N B. 1.4 N C. 2.8 N D. 3.5 N 4) A truck loaded with sand accelerates along a highway. The driving force on the truck remains constant. What happens to the acceleration of the truck if its trailer leaks sand at a constant rate through a hole in its bottom? A. It decreases at a steady rate. B. It increases at a steady rate. C. It increases and then decreases. D. It decreases and then increases. E. It remains constant.
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Since raindrops grow as they fall, their surface area increases and therefore the resistance to their falling increases. A raindrop has an initial downward velocity of $ 10\;m/s $ and its downward acceleration is $$ a = \left\{ \begin{array}{ll} 9 - 0.9t & \mbox{if $ 0\leqslant t \leqslant 10 $}\\ 0 & \mbox{if $ t > 0 $} \end{array} \right. $$ If the raindrop is initially $ 500\;m $ above the ground, how long does it take to fall?
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Since raindrops grow as they fall, their surface area increases and therefore the resistance to their falling increases. A raindrop has an initial downward velocity of $10 \mathrm{~m} / \mathrm{s}$ and its downward acceleration is $$a=\left\{\begin{array}{ll} 9-0.9 t & \text { if } 0 \leqslant t \leqslant 10 \\ 0 & \text { if } t>10 \end{array}\right.$$ If the raindrop forms $500 \mathrm{~m}$ above the ground, how long does it take to fall?
A 3.00 g bullet traveling horizontally at 400 m/s hits a 3.00 kg wooden block which is initially at rest on a smooth horizontal table. The bullet buries itself in the block without passing through. The speed of the block after the collision is a) 0.4 m/s. b) 1.2 m/s. c) 2.0 m/s. d) 2.8 m/s. e) 3.6 m/s. 2. What type of collision was seen in the previous problem? a) elastic collision b) inelastic collision c) perfectly elastic collision d) perfectly inelastic collision 3. A cubic meter (m^3) of water has a mass closest to a) 1 kg b) 10 kg c) 100 kg d) 1000 kg e) 9800 N 4. Two objects are in direct contact with each other. Object A is currently at a temperature of 20 °C, while object B is at 90 °C. Which of the following correctly indicates the direction of heat flow, and the method of heat transfer? a) A to B; convection b) A to B; conduction c) B to A; convection d) B to A; conduction e) Heat does not flow in this situation 5. A 9.3 kg object is dropped from a height of 3.2 m above the ground. How much kinetic energy does it have just before it hits the ground? a) 7.92 J b) 29.76 J c) 31.36 J d) 291.6 J 6. You are throwing a ball straight up in the air. At its highest point, the ball's a) velocity and acceleration are both zero b) velocity is nonzero but its acceleration is zero c) acceleration is nonzero but its velocity is zero d) velocity and acceleration are both nonzero 7. Voltage is a term that we use to represent a change in a) temperature b) electric potential energy c) voltage d) electric potential e) charge 8. An impulse of 5.0 kg m/s acts on a crate. Which of the following is an equivalent value for this impulse? a) 5.0 x 10^4 g cm/s b) 5.0 x 10^5 g cm/s c) 5.0 x 10^6 g cm/s d) 5.0 x 10^7 g cm/s e) 5.0 x 10^8 g cm/s
Prem B.
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