Physics 305
Newton's Laws - Additional Problems
1. An automobile has a mass of 1600 kg. What force is required to give it an
acceleration of 1.2 m/s2 if there are frictional forces totaling 200 N?
2. A force of 10N is applied to a body of mass 4 kg which is on a perfectly smooth horizontal surface.
Find the velocity of the body and the distance it has traveled after 6 s.
3. A body of mass 4 kg with an initial velocity of 15 m/s comes to rest in a distance of 20 m when a
certain resistive force acts on it. What is the magnitude of this resistive force?
4. A bullet of mass 20 g moving horizontally at 400 m/s, strikes a target and penetrates 16mm. Calculate
(a) the deceleration of the bullet on penetration, (b) the average resistive force offered by the target.
5. A vehicle of mass 400 kg traveling at 144/hr is brought to a stop in 8 s. Calculate (a) the deceleration
of the vehicle, (b) the braking force applied, (c) the distance to stop.
6. A mini- bus of mass 6000 kg is decelerated from 72 km/hr to 18 km/he in
7.5 s by the application of the brakes. Determine (a) the deceleration,
assumed uniform of the minibus, (b) the braking force, (c) the distance
traveled while the brakes are on.
7. A body of mass 15 kg rests on a frictionless surface and has a 30 N force applied to it. (a) What
acceleration is produced? (b )What will its velocity be at the end of 10 s? (c) How far will the body
travel in 10 s?
8. An object of mass 50 kg is at rest at the origin (x = 0) on a horizontal frictionless surface. At time t =
0 a force of I0N is applied to the object in the horizontal direction for 5 s. (a) What are the position
and velocity of the object at t = 5 s? (b) lf the same force is again applied at t = 15 s, what are
the position and velocity of the object at t = 20 s?
Answers
1.
Fa =
2120 N
2.
3.
4.
5.
6.
7.
8.
Vf= 15 m/s, d=45 m
Ff = -22.5 N
a = -5 x 106 m/s2 F = 1 x 105 N
a = - 5 m/s2, Fb = -2000 N, d = 160 m
a = -2 m/s2, Fb =-12000 N, d = 93.75 m
a= 2 m/s2, Vf= 20 m/s, d = 100 m
a) d = 2.5 m, v = 1 m/s b) d = 20 m, 2m/s
Newton's laws of motion Additional Questions II
1. What net force is required to accelerate a 1500 kg race car at 3.0 x 10 2 m/s ?
2. An artillery shell has a mass of 55 kg. The shell is fired from a gun, leaving the barrel
with a velocity of 770 m/s. The gun barrel is 1.5 m long. Assume that the force, and thus
the acceleration is constant while the shell is in the gun barrel. What is this force?
3. When a shot-putter exerts a net force of 140 N on a shot, the shot has an
acceleration of 19 m/s2. Determine the mass of the putt?
4. Together a motorbike and a rider have a mass of 275 kg. The
motorbike is slowed with an acceleration of -4.50 m/s2. What is
the net force on the motorbike?
5. A car, mass 1225 kg, traveling at 105 km/h, slows to a stop
in 53 m. What is the magnitude and direction of the force that acted on the car?
6. Imagine a spider with mass 7.0 x 10-5 kg moving downward on its thread. The
thread exerts a force that results in a net upward force on the spider of 1.2 x 10 -4.
What is the acceleration on the spider?
7.
A certain sports car accelerates from 0 to 100 km/h in 9.0 s. The mass of the car
is 1354 kg. The average backward force due to air drag during acceleration is 280 N.
Find the force required to give the car this acceleration?
8. A force of 9.00 x 103 N is used to stop a 1500 kg car traveling at 72 km/h. What
braking distance is required to being it to a stop?
9.
A 5.2 kg bowling ball is accelerated from rest to a velocity of 12 m/s as the
bowler covers 5.0 m of approach before releasing the ball. Determine the force exerted
on the ball during this time.
10. A high jumper, failing at 4.0 m/s, lands on a foam pit and comes to a stop,
compressing the pit 0.40 m. If the pit is able to exert an average force of 1200 N on the
high jumper in breaking the fall what is the jumper's mass?
Answers
1. 4.5 x 105 N
2. 1 x 107 N
3. 7.4 kg
4. -1240N
5. -9800 N
6. 1.7 m/s2
7. 4.4 x103 N
8. 33 m
9. 75 N
10. 65 kg