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ENGINEERING MECHANICS-DYNAMICS

An auto,equipped with only wheel brakes, has a wheelbase of 120 in. with its c.g. located 60 in. ahead of the rear wheels and 36 in. above the pavement. If f = 0.80 at the tires, compute the minimum distance in which the auto can be brought to rest from a speed of 60 mph if the driver’s reaction time before applying the brakes is 3/4 sec.

ENGINEERING MECHANICS-DYNAMICS

A car with a four-wheel drive weighs 3000lb and has a wheelbase of 10 ft. The c.g. is 3 ft above the pavement and 4 ft ahead of the rear wheels. Compute the tractive force acting at the rear wheels when the car accelerates at 1/3 g ft per sec2_{. Assume the coefficient of friction is}

ENGINEERING MECHANICS-DYNAMICS

The coefficient of kinetic friction under the sliding supports at A and B in Fig. P-1083 is 0.30. What force P will give the 600-lb door a leftward acceleration of 8.05 ft per sec2 _{? What will}

ENGINEERING MECHANICS-DYNAMICS

ENGINEERING MECHANICS-DYNAMICS

Determine the value of W in Prob. 1087 if the 200-lb crate is on the verge of tipping forward as it slides up the incline. Assume d = 3.32 ft.

ENGINEERING MECHANICS-DYNAMICS

The frame of a machine is accelerated leftwards at 3/5 g ft per sec2_{. As shown in Fig.}

P-1089, it carries a uniform angle ABC weighing 80 lb which is braced by the uniform strut Cd weighing 60 lb. Determine the components of the pin pressure at C upon CD.

ENGINEERING MECHANICS-DYNAMICS

Repeat Prob. 1089 if the frame of the machine is accelerated rightwards at 4/5 g ft per sec2_.

ENGINEERING MECHANICS-DYNAMICS

The uniform bar AB weighing 240 lb is mounted as shown in Fig. P-1091 upon a carriage weighing 480 lb. The center of gravity of the carriage is at C midway between the wheels. If P = 180 lb and there is no frictional resistance at the wheels, find R1 and R2 and also the horizontal

ENGINEERING MECHANICS-DYNAMICS

Repeat Prob. 1091 if the magnitude and sense of P is such that the reaction of the carriage upon the bar at B is 60 lb leftwards.

ENGINEERING MECHANICS-DYNAMICS

Two bodies A and B, each weighing 96.6 lb,are connected by a rigid bar of negligible weight attached to them at their gravity centers. The coefficients of reaction of the wall and floor reactions. Explain why these reactions pass though the gravity center of B and A respectively. Hint: Relate the acceleration by the method developed in Illus. Prob. 1018 on p. 258.

ENGINEERING MECHANICS-DYNAMICS

ENGINEERING MECHANICS-DYNAMICS

The initial angular velocity of the compound pulley B in the figure is 6 rad per sec counterclockwise and weight D is decelerating at the constant rate of 4 ft per sec2_{. What distance}

ENGINEERING MECHANICS-DYNAMICS

A flywheel 6 ft in diameter accelerates from rest at the constant rate of 4 rpm per sec. Compute the normal and tangential components of the acceleration of a particle on the rim of the flywheel after 10 sec.

ENGINEERING MECHANICS-DYNAMICS

The rim of a 50-in wheel on a brakeshoe testing machine has a speed of 60 mph when the brake is dropped. It comes to rest after the rim has traveled a linear distance of 6000 ft. What are the constant angular acceleration and the number of revolutions the wheel makes in coming to rest?

ENGINEERING MECHANICS-DYNAMICS

A gear is accelerated from rest to a speed of 900 rpm and then immediately decelerated to a stop. If the total elapsed time is 10 sec, determine the total number of revolutions of the gear. Assume that both acceleration and deceleration are constant but not necessarily of the same magnitude.

ENGINEERING MECHANICS-DYNAMICS

When the angular velocity of a 4-ft diameter pulley is 3 rad per sec, the total acceleration of a point on its rim is 30 ft per sec2_{. Determine the angular acceleration of the pulley at this}

ENGINEERING MECHANICS-DYNAMICS

Determine the horizontal and vertical components of the acceleration of point B on the rim of the flywheel shown in the figure. At the position, ω= 4 rad per sec and = 12 rad per secɑ 2_,

ENGINEERING MECHANICS-DYNAMICS

ENGINEERING MECHANICS-DYNAMICS

A pulley has a constant angular acceleration of 3 rad per sec2_{. When the angular velocity}

is 2 rad per sec, the total acceleration of a point on the rim of the pulley is 10 ft per sec2_{. Compute}

ENGINEERING MECHANICS-DYNAMICS

The step pulleys shown in the figure are connected by a cross belt. If the angular

acceleration of C is 2 rad per sec2_{, what time is required for A to travel 180 ft from rest? Through}

ENGINEERING MECHANICS-DYNAMICS

ENGINEERING MECHANICS-DYNAMICS

The rod BO in the figure rotates in a vertical plane about a horizontal axis at O. At the given position, end B has a downward vertical component of velocity of 6 ft per sec and also a downward vertical component of 9 ft per sec2_{. Compute the angular acceleration of rod BO and}

ENGINEERING MECHANICS-DYNAMICS

A body rotates according to the relation = 3tɑ 2_{+4, displacement being measured in}

radians and time in seconds. If its initial angular velocity is 4 rad per sec and the initial angular displacement is zero, compute the values of ω and for the instant when t= 3 sec. ϴ

ENGINEERING MECHANICS-DYNAMICS

The rotation of a pulley is defined by the relation = 2tϴ 4_-30t2_{+6, where is measured in ϴ}

radians and t in seconds. Compute the values of angular velocity and angular acceleration at the instant when t= 4 sec.

ENGINEERING MECHANICS-DYNAMICS

The rotation of a flywheel is governed by the equation ω= 4

√ t

ENGINEERING MECHANICS-DYNAMICS

A body rotates according to the relation = 2t, where is in radians per second and t is in ɑ ɑ seconds. ω= 4 rad per sec and is zero when t is zero. Compute the values of ω and at the ϴ ϴ instant when t= 2 sec.

ENGINEERING MECHANICS-DYNAMICS

Determine the number of revolutions through which a pulley will rotate from rest if its angular acceleration is increased uniformly from zero to 12 rad per sec2 _{during 4 sec and then}