Exam 4: Applying Newtons Laws

Two blocks,A and B,are being pulled to the right along a horizontal surface by a horizontal 100-N pull,as shown in the figure.Both of them are moving together at a constant velocity of 2.0 m/s to the right,and both weigh the same. Which of the figures below shows a correct force diagram of the horizontal forces exerted on the lower block,B?

A boy kicks a football with an initial velocity of 20 m/s at an angle of 25° above the horizontal.If we neglect air,the magnitude of the acceleration of the ball while it is in flight is

A 3.0-kg and a 5.0-kg box rest side-by-side on a smooth,level floor.A horizontal force of 32 N is exerted on the 5.0-kg box pushing it against the 3.0-kg box,and,as a result,both boxes slide along the floor.How hard do the two boxes push against each other?

Jason takes off across level water on his jet-powered skis.The combined mass of Jason and his skis is 75 kg (the mass of the fuel is negligible).Water exerts a force of 200 N on the skis.The coefficient of kinetic friction between the skis and water is 0.10.Unfortunately,the skis run out of fuel after only 41 s.How far from his starting point has Jason traveled when he finally coasts to a stop?

A certain aircraft has a mass of 300,000 kg.At a certain instant during its landing,its speed is 27.0 m/s.If the stopping force exerted on the airplane is a constant 445,000 N,what is the speed of the airplane 10.0 s later?

An athlete participates in an interplanetary discus throw competition during an Olympiad that takes place on a planet where the free-fall acceleration is 9.7 m/s².He throws the discus with an initial velocity of 20 m/s at an angle of 60° from the vertical.Neglecting air resistance and the height of the discus at the point of release,what is the range of the discus?

For general projectile motion if we neglect air,the horizontal component of a projectile's acceleration

A rock is thrown from the upper edge of a tall cliff at some angle above the horizontal.It reaches its highest point and starts falling down.Which of the following statements about the rock's motion are true just before it hits the ground? (There could be more than one correct choice.)

The components of vectors $\vec { B }$ and $\overrightarrow { \mathrm { C } }$ are given as follows: $B _ { x }$ = -9.2 $C _ { x }$ = -4.5 $B _ { y }$ = -6.1 $C _ { y }$ = 4.3 The angle (less than 180°)between vectors $\vec { B }$ and $\overrightarrow { \mathrm { C } }$ is closest to

A hockey puck slides off the edge of a platform with an initial velocity of 20 m/s horizontally.The height of the platform above the ground is 2.0 m.What is the magnitude of the velocity of the puck just before it touches the ground? You can neglect air.

A projectile is fired from ground level at an angle above the horizontal on an airless planet where g = 10.0 m/s².The initial x and y components of its velocity are 86.6 m/s and 50.0 m/s respectively.How long after firing does it take before the projectile hits the level ground?

A stone is thrown horizontally with an initial speed of 10 m/s from the edge of a cliff.A stopwatch measures the stone's trajectory time from the top of the cliff to the bottom to be 4.3 s.What is the height of the cliff if effects of air are negligible?

A boy throws a rock with an initial velocity of $3.13 \mathrm {~m} / \mathrm { s }$ at 30.0° above the horizontal.How long does it take for the rock to reach the maximum height of its trajectory if effects of air are negligibly small and g = 9.80 m/s²?

A child throws a ball with an initial speed of 8.0 m/s at an angle of 40° above the horizontal.The ball leaves her hand 1.0 m above the ground.At what angle below the horizontal does the ball approach the ground assuming no effects of air?

The x component of vector $\vec { A }$ is 5.3 units,and its y component is -2.3 units.The angle that vector $\vec { A }$ makes with the +x-axis is closest to

A 5.0-kg box slides on the surface on a ramp that rises at 37° above the horizontal.The coefficient of kinetic friction between the box and the surface of the ramp is 0.60.What are the magnitude and direction of the acceleration of the box if it is sliding (a)up the ramp,(b)down the ramp?

In a room where g = 9.81 m/s²,a hockey puck slides off the edge of a platform with an initial velocity of 28.0 m/s horizontally.The height of the platform above the ground is 2.00 m.What is the speed of the puck just before it hits the ground? Ignore air.

Mary and Debra stand on a snow-covered roof.They both throw snowballs with the same initial speed,but in different directions.Mary throws her snowball downward,at 30° below the horizontal; Debra throws her snowball upward,at 30° above the horizontal.Which of the following statements are true about just before the snowballs reach the ground below? Neglect the effects of air.(There could be more than one correct choice.)

A boy throws a ball with an initial velocity of 25 m/s at an angle of 30° above the horizontal.If you neglect air,how high above the projection point is the ball after 2.0 s?

The figure shows a block of mass m resting on a 20° slope.The coefficients of friction between the block and the surface of the slope are $\mu _ { \mathrm { S } } = 0.64$ and $\mu _ { \mathrm { k } } = 0.54$ It is connected using a very light string over an ideal pulley to a hanging block of mass 2.0 kg.The string above the slope pulls parallel to the surface.What is the minimum mass m so the system will remain at rest when it is released from rest?