A truck is using a hook to tow a car whose mass is one quarter that of the truck

Question

A truck is using a hook to tow a car whose mass is one quarter that of the truck. If the force exerted by the truck on the car is 6000 N, then the force exerted by the car on the truck is 1500 N 24000 N 6000 N 12000 N We need to know if the car is accelerating to answer this question. You are standing in a moving bus, facing forward, when you suddenly slide forward as the bus comes to an immediate stop. What force caused you to slide forward? gravity the normal force due to your contact with the floor of the bus the force due to friction between you and the floor of the bus There is not a force causing you to slide forward. A person is using a rope to lower a 5.0-N bucket into a well with a constant speed of 2.0 m/s. What is the magnitude of the force exerted by the rope on the bucket? 0.00 N 2.0 N 5.0 N 10 N 49 N A person who normally weighs 700 N is riding in a rather swift elevator that is moving at a constant speed of 9.8 m/s. If this person is standing on a bathroom scale inside the elevator, what would the scale read? more than 700 N less than 700 N 700 N It could be more or less than 700 N, depending on whether the elevator is going up or down. A 75-N box rests on a perfectly smooth horizontal surface. The minimum force need to start the box moving is 75 N. 7.5 N 750 N. any horizontal force greater than zero. Two small balls, A and B, attract each other gravitationally with a force of magnitude F. If we now double both masses and the separation of the balls, what will now be the magnitude of the attractive force on each one? 16F 8F 4F F F/4

Explanation / Answer

27) The force exerted by the car on the truck is equal to the tension T in the hook which is same of the the force exerted by the truck on the car

the system of the truck and car is at rest. The horizontal forces acting on the system are equal and opposite so,

force  exerted by the car on the truck =force exerted by the truck on the car =6000 N

answer is option (C)

28)The person falls forward due to the force of static friction between him and the floor of the bus.

the reason for it can be explained by Newton's first law of motion . An object at rest or moving at a constant

velocity continues to do so unless it it is acted upon by a force. When the person is moving in the bus velocity is

constant. A sudden deacceleration of the bus as it comes to rest does not effect the person and he continues to

move at the constant velocity.In the absence of friction the person would slide on the floor and his motion would

be stop only when an obstacle is encounterd

This is does not happen as there is friction between the person's feet and floor of the bus. This does not

allow the the feet to continue to move freely through the person's body is not stopped in any way.The result is

the person falling forward

so answer is option (C)

29) Since the bucket is moving at a constant speed ,it is not accelerating. This means the net force force on the bucket is 0 N. For this to be true ,the magnitude of force exerted by the rope must be equal to the weight of the

bucket i.e 5 N

F(force exerted by the rope on the bucket ) =mg =5.0 N (there is no other kind of force like F=ma in the picture because a=0 )

so answer is option (C)

30) The scale reading is actually measure of the upward force applied by the scale to balance the downward force of gravity acting upon an object when the object is in state of equilibrium

here the elevator is moving with constant speed so the system is in equilibrium state. In equilibrium state the reading of scale is equal to the weight of the person

scale read = weight of the person =700 N

Answer is option (C)

31)The box is at rest ,and so the only force acting on the box is weight pulling it down to the table and the normal force acting against the weight of the box. These two forces equal and cancel each other .

There is no friction between the box and the floor so F =(mu) N =0 ( mu =0)

ther is no horizontal force acting on the box , if we applied any non-zero force on the box it causes the motion of the box

Answer is option (D)

32)the gravitational force btween the two masses m1,m2 which are separated by a distance R is

F1 =K ( m1xm2)/(R2) --------------------(1)

if m1 ,m2 and R are doubled then force becomes

F2 =K (2m1x2m2)/(2R)2 = K(m1xm2) /(R2) =F1

the force between the masses will not change

answer is option (D)

  

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