Answer 55.16 m

70.8 Problem
A wooden block starting from rest, slides 6 m down a 45˚ slope, the 3 m along a level surface
and then up a 30˚ incline until it comes to rest again. If the coefficient of friction is 0.15 for all surfaces of
contact, compute the total distance travelled.

70.9 Problem
The block shown started at rest and moves towards the right. What is the velocity of block B as
it touches the ground? How far will block A travel along the horizontal surface if the coefficient of friction
between block A and the surface is 0.20?Assume pulley to be frictionless.

70.10 Problem
After the block has moved 3 m. from rest, the constant force P = 600 N is removed. Find the
velocity of the block when it returns to its initial position.

70.11 Problem
A 10 –kg block is raised vertically 3 meters. What is the change in potential energy? Answer in
SI units closes to:

70.12 Problem

A car weighing 40 tons is switched to a 20% upgrade with a velocity of 30 mph. If the car is
then allowed to run black, what velocity will it have at the foot of the grade?

70.13 Problem
A 200 ton train is accelerated from rest to a velocity of 30 miles per hour on a level track. How
much useful work was done?

70.14 Problem
A drop hammer weighing 40 Kn is dropped freely and drives a concrete pile 150 mm into the
ground. The velocity of the drop hammer at impact is 6 m/sec. What is the average resistance of the soil in Kn?

70.15 Problem
A car weighing 12 Kn including its cargo in moving down a
30˚ slope. The driver sees an
obstruction way ahead, so he applies the brakes at the instant that his speed is 20 m/s. What constant force
parallel to the road must be provided by the brakes so that the car should stop in a distance of 100 m.

71.1 Problem
A 1 N bullet is fired with a velocity of 900 m/sec. into an 89 N sand box mounted on wheels.
After the impact, the box strikes a spring and is brought to rest in a distance of 150 mm. Find the spring
constant.

71.2 Problem
A 3000 N block slides down an incline having a slope of 3 vertical to 4 horizontal. It starts from
rest and after moving 1.2 m strikes a spring whose modulus is 1500 N/m. If the coefficient of kinetic friction is
0.20, Find the maximum velocity of the block?

71.3 Problem
A block weighing 500 N is dropped from a height of 1.2 m. upon a spring whose modulus is 20
N/mm. What velocity will the block have at the instant the spring is deformed 100 mm?

71.4 Problem
A 50 kg object strikes the unstretched spring attached to a vertical wall having a spring
constant of 20 KN/m. Find the maximum deflection of the spring. The velocity of the object before it strikes the
spring is 40 m/s.

71.5 Problem
A large coil spring with a spring constant k = 120 N/m is elongate , within its elastic range by 1
m. Compute the stored energy of the spring in N.m.